[Davescort97]

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Sounds like you have a vacuum leak. Start at the intake plenum and backtrack the vacuum hoses to cure leak. Check the PCV valve, hose and elbow at the intake. Elbow is plastic and has been known to be cracked. Check the rubber intake hose from the air cleaner to the throttle body for cracks or holes. Sililcon sealer will fix any that you find. IAC (Idle Air Control) is supposed to send more air through the engine to compensate for an additional load such as A/C or Alternator. Clean the terminals to it and take it off and spray some WD40 into the 2 chambers. It is located on top of the throttle body. To check for a vacuum leak put a vacuum gauge on any intake port and it should read 18 to 20 inches at idle. If it has less than that you have a leak or the catalytic converter is plugged or the muffler is plugged. If you have normal power at speed this can be ruled out. Anybody else out there? This is a forum!