My 00 Impreza 2.2L has periodic CEL, with the code being the IAC. I took it out, several times, really cleaned it up well, and reinstalled. Car runs fine, than for no reason, CEL comes back on idle smoothly surges between 300-800 rpm when coming down from speed to idle. CEL disappers again in a day or two, car running fine. Could the culprit be the throttle position sensor? I am unable to detect any vacuum leak. Thanks
