[jsgold]

The IAC valve might be dirty or maybe someone worked on the car recently and never ran it so the computer could re learn the idle speed. If it keeps acting up remove the battey, remove the IAC, clean it carefully and the area it sits in, and replace any hoses you can get at. Then hook up and let it idle for a while. There is a more proper idle relearn procedure but if you run it the computer eventually adjusts it Ok.