Misfire at idle - P0301

[PSYKO_Inc]

I've searched quite a bit but haven't found a definitive answer. The car is a 2000 SL1 automatic with 112K. When it's moving the car runs great, but it has a slight stumble at idle. The stumble gets worse when the car is in park or neutral, and seems to run a bit better when I shift it into drive. It has plenty of power and drives great, just took it on a trip to SoCal and it had no problems maintaining 80mph on the freeway for hours at a time and giving me about 40mpg. It only throws the code when I leave the car idling for several minutes. I have installed new Autolite copper plugs and Bosch wires, and the valve cover gasket isn't leaking. Any ideas?

[rickystarshine]

It could be an intake manifold gasket leak, this is a known problem on the 2000-2002 SOHC engines(like yours)
To test for this, start the car, spray brake cleaner at the intake manifold where it meets the head, behind the power steering pump(cylinder 1)
if you hear a change in idle speed, you have a leaking gasket, replace it.

[eRic 02sc2]

A code P0301 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer