nick_thames

Hopefully you guys can help!

Ive got a 2003 GT automatic. Lately I noticed that the cars engine while under normal stop and go traffic, the engines RPM dropped to around 500 under braking and rise to 750. The car used to idle and run around 1000 sitting.

Two things I noticed. First is that while driving at highway speeds with 3:73's my car is above 2,000 RPM. Once i let off the gas and the rpms dip below 2000, I feel a jerky type feel and the car drops 500 rpm almost instantly. Its aggravating when this happens because when i hit the gas the rpms rise back to where they shouldve been.

secondly, i can click the car into neutral, and the rpms go haywire. the car will go from 1200rpms and drop to 500, then rise and fall again. Its like the car wants to stall but kicks back on. Cant figure it out for the life of me.

I replaced the pcv tube that runs from the passenger side valve cover to the intake elbow. Ive also tried cleaning the blades on the throttle body.

What else could it be. Thanks for your help!

stevednmc

Sounds like you have an issue with the IAC (idle air control) motor. Sounds pretty typical of the issue you having. You would be best to replace it, with a FoMoCo part. Some have had luck cleaning them, but its a stop gap at best, if it even works at all. There are tons of thread on this forum related to the IAC. Pretty easy part to replace, right on the upper intake plenum toward the driver side next to the TPS. I think the part is somewhere around 125-150 bucks though. Maybe try disconnecting your battery for 10 minutes and drive it around to reset the KAM. (keep alive memory) as well.....or first....