car idles perfect, doesnt stall or over rev. replaced iacv and power steering air control valve, took the car to a well know shop being Aamco in st Louis mo, they said fault was lying with power steering air control valve, replaced that part as well. took the car back and had them reset and remove check engine light codes, what else could be the cause
Code P0505 stands for Idle Air Control (IAC) Malfunction. Anything that affects the idle control system could be the cause. This could be anything from the IAC control circuit (PCM, wiring, etc.) to a mechanical problem such as a vacuum leak. A good diagnostic technician will be able to pinpoint the problem instead of just throwing parts at the vehicle. Have an expert inspect the Check Engine Light in person so that you can have this fault corrected.