Engine Performance problem
1990 Chevy Corvette V8 Two Wheel Drive Automatic 22000 miles
I have 1990 Corvette 5.7L Automatic, 22000 mile, that runs fine when I get on the gas but surges on slow idle and almost seems like it's going to stall. Come to a light or stop sign, I have to put it in neutral or park so the idle will be a little faster to solve the slow idle problem. This only happens when it is warmed up and the slow idle drops to 500 rpms when the car stops. I replaced the following parts and the problem still exists:
Coolant temperature sensor
Throttle postition switch
Cleaned the throttle body
Replaced Oxygen sensor
Replaced IAC valve
No codes are present in the ECM. I would appreciate any help you can give me with this problem.
You may have to reset minimum air rate a little higher. To set base idle on this car you need to have engine warm and idle air control valve seated, to do this jump a and b on the aldl connector. Then set base idle to 650-700 rpms. See if this helps. There are tone of thing s that can cause rough idle but lets start there.