Verified answer

It may also be the fuel filter have it changed if this doesn't fix it then it may be the Idle air control valve this can either be cleaned off or replaced although cleaning is a temporary fix

A stuck or bad idle air conrtol valve is usually siginified by a stall when driving at a reasonable speed and letting off the gas to make a turn or stopping, I would first check your Mass Air Flow senson as well as your filter, if none of these are the culprit check the car for vacuum leaks, a leaking pcv valve will sometimes cause this kind of idleing problem.

There are numerous possibilities.....pirate air entering into the system after the airflow meter( bellows cracked etc..) the

system could be searching for a mixture going from way lean to very rich which will drive the Oxygen Sensor crazy by trying to adjust the fuel mixture to both extremes thus causing the idle to go up and down.... good luck

idle air contol motor most likely