Hi, Me and the girlfriend just got a 99 Celica GT to replace her 94 ST.

The cars idle has been low at about 500RPM. Yesterday while driving I just noticed that the temp gauge while driving drops down. (I did not let it idle and see if it stayed low).

While I figure I'm going to do the Thermostat when I get a chance I was wondering if there's a chance it was affecting the idle. If not is there usually a smoking gun with the Celicas on the low idle. I just wanted to ask here first to see what else I should check at the same time.

Thanks for any help.

clean up the throttle body and all the valves under it. probably the IAC valve gummed up