jimmydean

I have an 05 cobalt that I just purchased. It was not running, it had a security issue that ended up being the TCM. Bought a used TCM for $29 shipped and had the stealership reprogram it for $100, now it's running. However, it runs like crap at idle and especially when it's cold, but runs great above 2000 rpm or so. It's throwing a p0507 code, which comes back instanly after being cleared.

From obd-codes.com:

Causes

A P0507 DTC trouble code may be caused by one or more of the following:

A vacuum leak
Leaking air intake after the throttle body
EGR valve leaking vacuum
A faulty positive crankcase ventilation (PCV) valve
Damaged/failed/dirty throttle body
Failed EVAP system
Failed IAC (idle air controller) or faulty IAC circuit


My mechanic didn't find any vacuum leaks, checked the egr and pcv, cleaned throttle body, and also replaced the intake gaskets just in case. This did not help. The code comes back instantly after it's cleared.

I'm leaning towards replacing the throttle body with a used one since it has the idle air control built into it... any other suggestions, or does this sound like the way to go for now?