FWIW, I hard a hard time getting my IAC to settle down and finally figured out I was adjusting it with the air cleaner off and the car around 170°F, and it looked good. As the car got hotter and the car reached over 190°F the settings would change. Two things were happening, the air cleaner changed the air flow, and as the engine compartment got hot and the IAC heated up, it expanded and the adjustments changed. What I did was got the car good & hot, adjusted the IAC and then over adjusted just a little bit to compensate for when the air cleaner was put back on.