I have a 2003 ecotech with 75000 on it. It runs and drives good but has an idle problem. It normally does it when the a/c is on, sometimes not. It will idle fine for 10 seconds or so then pop or miss then idle for a few more seconds and do it again. Its pretty sporadic but seems to do it more when the motor is under load at idle. I have cleaned the IAC figuring it might be the culprit but I did not have any luck. It has no problems starting hot or cold, and goes good down the highway. I'm getting pretty frustrated with this so any help would be greatly appreciated.