Rough Idle when hot, car won't start, underhood polyloom crispy

[BLH RS4TC 4040]

Hello folks, I got one for ya today... my 2008 Aura XE 3.5L recently experienced a stuttering as I pulled off the highway on my way to work. I chalked it up to having 1/8 tank of gas in the wonderful Michigan winter. I was actually going to get gas at a station near work a few miles further down the road where it is 40 cents/gal cheaper, but thought otherwise the way it was running. I thought maybe I stirred up some sediment in the bottom of the tank by letting it run so low. I've had it run lower with no problems, but it IS 15 years old with 168,000 miles on it, so I filled it up hoping that would work. It did seem to because after starting it, it immediately ran smoother. OK I thought, just don't let it run down so low again. Well, a mile away from my work while stopped at a stop light, it started it's rough idling again. Great... probably water in the gas tank cuz I had let it run so low in the wonderful Michigan winter, I thought. I made it to work and at lunch started it up to test something out. It started up wonderfully like usual with no idling problems. I ended up getting it warmed up and that's when it happened again. I put it back into park and figured I'd deal with it after work. So after work, it started up fine and I drove to O'Reilly's to pick up some dry gas. In my over 30 years of driving I've used dry gas like 5 times.
Never in the past 25 years! I put a bottle in the tank and drove home. I took the back roads home due to where I was at the time but didn't notice any problems. The next day, no problems either going to and from work. The dry gas must've done the trick, right? Nope.

The next day I made it to work no problem but on the drive home, the issues reared their ugly heads! I decided to take the freeway home that day and after getting stuck behind a semi doing 60 mph for a few miles, I saw a spot where I could get over and pass it. When I did, my car sped up like normal... then sputterered... I couldn't get past 60 mph myself! Cars were starting to come up behind me now and after a good goose on the gas pedal, my car surged but then sputtered back to 60 again. The guy behind me had to be furious! I ended up taking the median shoulder until traffic cleared, then prayed I could make it to the right shoulder (which I did). I was 1/4 mile from an exit ramp where there's a grocery store right off the highway. I planned on pulling in there to assess what was going on. I didn't make it that far. After turning onto the road from the e-way, I got about halfway to that driveway and the car stalled. Luckily, there was a driveway between 2 fast food joints and NO traffic coming my way so I was able to coast right on in and pull over. I tried starting the car back up but all it did was crank and it felt like it wasn't even trying to catch. I did notice something odd when it did that- the ignition felt like it was sticking and I had to pull it back to "on" or else I would've burned up the starter! It had never done that before (nor any other time). After Allstate telling me it would be at least 2 hours for the nearest "rescuer" could come get me from clear across the other side of Detroit, I walked over to the gas station to grab something to drink. Upon return, I figured what the heck, and it started right up. After letting it run for a couple of minutes and no adverse effects from goosing the gas a little, I canceled my tow that was still an hour-15 out and was able to drive it all the way back home (about 12 miles from there) with no problems. Upon arriving at home, it did seem to have that rough idle starting to come back, but I turned it off right away so as not to press my luck.

For some reason, my Innova code scanner will not work on my car anymore. It stopped working a couple of years ago, but works fine on my old van. I ended up saying a prayer that I could make it up to my local O'Reilly's to have them scan the codes. P0011 and P0016 (intake camshaft position system performance and crankshaft position intake camshaft position not plausible). I did a lot of reading online since there are no commercially available manuals for the Aura. It's possible one of those two (most likely the cam sensor) might be bad, but it's also possible the wiring or the variable valve timing solenoid might be stuck/bad. I was out today while it was snowing trying to figure out what the actual problem was but found something extremely disheartening and what possibly could be the end for Rudy. A great deal of the polyloom on the front and driver's side that protects the wiring harnesses would just crumble to the touch. The only spots that were saved were where the electrical tape gave it extra protection. The wires themselves actually looked a little dry too which is what's concerning me. What could cause so much heat under that hood where the polyloom disintegrated like that? My first thought was a plugged exhaust, but full disclosure: I've had a loud exhaust for the last three years as it has a big hole at the flex pipe and a flange rusted off. It'll cost me more to replace those two pieces than the car's worth, so I hadn't fixed it. That couldn't be the reason for the excess heat up front. There was nothing causing restricted airflow, nor did my temp gauge ever show signs of anything out of the ordinary (I know, it's engine oil temp not ambient underhood temp, but I'd still think if things were running hot, it would inch a little higher than normal at least).

I'm now at a crossroads. Should I continue on, inspecting all the wiring and connectors under the hood, possibly stumbling upon the cause of all my frustrations, repair it, only to possibly have whatever's causing the excess heat to ruin it all and completely waste my time and money, or should I cut my losses, toss a brick on the gas pedal and wave goodbye to Rudy as he sputters towards the river? (I'm joking I would never pollute the waterways like that... that car has a lot of rust!) 😉 This car is my daily driver and even though it's been a pain when something goes wrong, it (was) still a reliable car with a lot of pep and decent on gas. Another thing I will do if I DO fix it would be to replace the plugs and wires (which have NEVER been replaced). It's due.

Does anyone have ANY recommendations as to what I should be looking for as far as what's causing the excessive heat, and if you think I'm on the right track by checking the wiring before replacing sensors and such. I'm working outside in the cold and snow so if its an invovled project, it'll take some time.
Money is tight right now so I can't afford a new car. My backup vehicle has been giving me problems too so I need at least ONE reliable vehicle. Any help would be greatly appreciated!

Thanks,
Dave

#OfCourseThisCrapOnlyHappensInTheWinter

[fdryer]

There are misconceptions even I presumed over the years when engine problems occur but each one was dispelled.

1- all gasoline are required to have at least 10% ethanol in 87 octane, regular gas. This means our cars, trucks and suvs have ethanol continually absorbing any moisture in fuel tanks. Dry gas is ethanol. It readily absorbs moisture. This makes it very rare for any vehicle to have water in its tank unless a severely rotted tank with an open hole allows rain water in. Ethanol in gasoline removes the need for dry gas. My guess is water isn't in your tank and not the cause of this intermittent problem. Most if not all gas tanks use a fuel sock to filter sediment from clogging expensive to replace in-tank fuel pumps.

2 check muffler or repair shops on costs to replace the flex coupling. They're usually welded unless the flex pipe has a flange for mounting to the exhaust system. Reasonable costs for just a flex pipe replacement may be between $50-$150. If diy, a sawzall cutting off the flex pipe, finding a longer replacement and using clamps may be a lower cost repair. The open hole isn't contributing to this problem, especially if it's downstream of both O2 sensors and zero O2 sensor error codes. Muffler cement with muffler tape may fix an open hole.

3- the P011 and P0016 may be the problem or pointing somewhere else. Alldata.diy or Mitchell data are online services for factory service manuals at reasonable fees. Some libraries may have free access to alldata. I'm not 100% familiar with variable cam timing using oil pressure to move cam timing. You should be able to find background info from past threads within these forums and online for possible issues like lack of oil changes affecting oil flow thru passages requiring oil pressure and metal filters in cam shaft solenoids possibly clogged with oil debris.

4- dry rot are normal for plastics as weathering and ozone eventually dries out plastics exposed to outdoor weather. New car smells were finally revealed some time ago as plastics cure thru outgassing..... chemicals evaporating during the life of every vehicle using plastics inside interiors. That new car smell is outgassing of new plastics curing. No one in the chemical community will discuss it openly on whether outgassing is harmful or not when inhaled. As plastics age, crumbling occurs. Heat, cold, fuel, oil and road salts accelerates the aging process. Any open hole in the exhaust system means hot exhaust gases of several hundred degrees may be cooking/burning nearby metal and plastics.

5- most engines with EFI systems allow spark plugs to run for 100k miles before recommending replacement. Plugs can last longer but conservative design considers the number of cylinder ignition cycles in the millions with thermal heat/cold cycles contributing to wear and tear where 100k miles is reasonable for replacing them for reliable performance. Keeping them well after 100k miles is a risk of anything unusual occurring with worn spark plugs.

I replaced mine at 100k miles (L300) and they looked new but prudence dictated replacing them when one of two coil packs failed. Several parts are removed before access to plugs so killing two birds with one stone was appropriate.