when the engine has warmed up the iac extends forward when reved then holds the throttle on return can takes about 10 seconds of fast idle before it returns in a jerking action i have just replaced the old iac as done the same thing.again no codes on self test.throttle action is good and cable is not stiff any idears?.
This is correct. The ISC acts as a dashpot to keep the throttle from returning quickly to the fully closed position. This is to keep the fuel mixture from going too rich during deceleration.
IAC is Idle Air Control. This is not what you have.
You have an Idle Speed Control motor, ISC.
Not sure if 10 seconds is too long a delay or not.
Make sure the ISC is adjusted for a 7/32" gap between the plunger tip and the throttle lever with the plunger fully retracted.
Install the self test jumper and ignition switch in run (KOEO) to retract the plunger.
Use a drill bit for a feeler gauge.
Disconnect the negative battery cable for 10 minutes to reset the EEC KAM
Start the engine and let it idle for 10 minutes to re-establish the EEC adaptive learning tables.
reset the isc and eec also checked tps and evp(which was high) now much better again thanks for the help.