Open exaust causing engine "miss"?????

I have a 94 SL2 and right now I have no muffler. I have a catalytic converter and a "cherry bomb" resonater in the stock location, but that's it (yes, I know, it's quite loud). When I rev the engine to 2000 rpms in neutral and hold it there, the engine misses consistently and rythmically. The air filter (K&N on SPS HotShot intake) is not clogged and I've recently changed my spark plugs, wires and PCM engine coolant temp sensor. The Throttle Body doesn't look dirty either. I've also recently changed my EGR valve.

I took it to the local Saturn dealership to have it diagnosed. They are telling me that they can't do an adequate test on the car because of the "custom" exaust. I had another dealership tell me a few months ago that my "custom" intake and exaust is causing the EGR and O2 sesnor to "act up".

I'm thinking, just change the O2 sensor and see what hapens, but I loathe "part changers". I'd rather have a complete test run to find the source of the problem and correct it.

What should I do?

Jon

[ssicarman]

Does the miss show up when you are driving the car or just in neutral when you rev it up? If only in neutral then don't worry about. 2000 RPM in neutral (not driving) is not a normal condition. Granted it should not do that but then you have modified the car and this certainly may cause the condition. If the miss is there driving then you need to keep looking for a problem.
Old joke but relevant here I think: Guy goes to the doctor and says "When I do this it hurts". Doctor says "Don't do that".

Isn't the no load rev-limiter different in Autos and manuals? I can see plenty of reasons for having it set low on an auto car in neutral...can anyone say neutral drops!!!!

Heheheheh. I have no idea if that's the probelm or not. When I opened up the exhaust and intake I incurred a "rear firing photon launcher" as one of my friends calls it. For about a month I had the cat off(no increase in anything besides noise, BTW) and between shifts a small blue'white flame would come out of the tail pipe, and then a POP sound...its not loud, not like a backfire...but a distinctive POP sound. After replaceing the cat, the flame departed, but not the occasional pop sound. The Air temp sensor is disconected...that may have something to do with it, I dunno.

[93KidCar]

Other than noise, what were you after by removing the CAT? Many many many magazine tests have shown that such mods do not do anything to help with power, since that is not the most restrictive part of the system these days. When cats first came out, that might not have been the case, but today, the systems are tested for thousands of hours and you're seeing the effects of messing with things. Besides, you're now dumping the combustion products into the atmosphere & that is just plain irresponsible.

[93KidCar]

Sorry, I misread what you had removed. I just couldn't believe that a Saturn owner would knowingly pollute.. I take that part back, but my comments about messing with the system stand.