The idling on my GT has been unstable since i purchased it almost 4 years ago so this year i decided to replace the IAC while it's in the shop well this was my plan before i got reading on how it works in relation with the ECM & CAT CONV.According to the spec i have been reading on start up the ECM measures the emisson temperature before it sets the proper idle rpm but my thing is my GT has no CAT CONV the prevoius owner removed it so now im wondering if it's worth the while to go ahead & replace the IAC