First check for vacume leaks. If none are found then remove IAC and clean it. Then clean your throtle body and air bypass screw would recomend removing it as carbon will build up inside the ports, clean that also. If you have a thermal fast idle valve check to see if it is still in adjustment, if not then adjust it. Then check your TPS voltage and make sure it is in spec, if not adjust it. then check you base timing. Also make sure your coolent system does not have any air pockets and topped of properly. After checking thses items and problem is still not solved let us know.