I can set my base idle while grounding the IAC but after I release the IAC ground the engine revs to 2000+ RPMs. I have to turn the black screw all the way in to get it down to 1000 so I can drive it.

Items replaced with junkyard parts (I have 4-5 of each part):
IAC(they could all be junk); FPR; Coil; Cap & rotor; ECU; Both fuel pumps; AMM; Injectors; All relays; ECT; EzK module; plus lots of other "stuff"...


It may be my inexperience with O2 sensors but mine seems to be responding slowly. Isn't it true, however, that it only contributes to the mixture equation when it reaches operating temp? The car exhibits this high idle problem even at first startup, before the car is even warmed up. The sensor moves the full range from .2 to .7 and responds to the lean and rich diagnostics as per the Ringlee FAQ's. It does NOT fluctuate while at idle, it stays at .7 until I induce a vacuum leak. It takes a few seconds for it to come down to .2.

I have NO vacuum leaks. Timing is dead on. FPR has a steady stream out of retrun hose. New fuel filter. I have yet to check fuel pressure ( see $$$$$ for details), but I really don't think this is the problem (I have tried 3 FPRs, 2 in-tank pumps and 3 main pumps in several combinations). Flame trap is immaculate. TB and intake manifold are spotless. New intake gasket. TB and TPS are adjusted correctly. New Bosch platinum plugs. New Bougicord wires. Rewired entire harness under hood.

I could have a bad part (possibly IAC) but I would like to have some suggestion as to which part I should buy new. I have been trying to avoid buying a $100 part only to find out that wasn't the problem.