After replacing my iacv with another used iacv the problem seemed to go away for about a week but now its back. Sometimes when I switch from park to reverse or reverse to drive my car shuts down. I went to meineke for them to diagnose the problem and of course it didnt do it once! He said even though I got the iacv code from the ecu it could just be a sensor sending the error to the iacv. I asked if I should just buy a brand new one and he said dont until he can diagnose the problem. So does anyone have any suggestions other than the iacv that could cause this very annoying problem?? Thanks

 

Check the ECT sensor, make sure it's resistance~vs~temp value is within spec.
Clean the throttle body and the IACV.
Check/adjust the default idle speed at the throttle body. (IACV disconnected)

The Haynes shop manual will help diagnoss your problem.