I have kind of the same problem. When I first start mine the runs varies from 1100 rpm to 500 to 800. Once the car warms up it seems to idle fine. Any help? I replaced all kinds of things including the ECM.
How do you know if the IAC is working properly? When I removed it and turned on the key the pintle retracted back. I was told it is working fine. Would love some input. Please respond.