Thanks guys. Do you think this could be the cause of my problem? I mean does the IAC affect the car like this? (How mine is acting.) Is it worth replacing?

Thanks again.

98 Black Mystique LS Duratec V6 2.5L ATX K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS. Mobil 1 5W-30