Lately my car has been having a rough idle on cold starts. When I start it the idle is at 1200 rpm and then its like the engine is misfiring because I can feel it shake and then the idle goes up to 1500rpm slowly idles down and then when it gets warm has a nice idle at around 750rpm. Anyone have any clues what can be causing this. Ive read it could be the ECT sensor but I'm not exacly sure where it is on our cars.

 

I had this same thing happen with Hackish's flash. It seemed to only happen if there was a drastic change in temperature from when I turned off the car and then started it back up again. When this would occur for the 2-3 seconds the wideband would read 18 + which means it was lean. I have since installed my stock ecu and haven't had any issues. I contacted hackish about this, but never really had a solution. At idle I doubt going lean was going to do any damage, but it can't be good everyday to be misfiring at idle like that. I wasn't going to take the chance. This is my experience.

 

It's really hard on the plugs to lean out like that, I would check my spark plugs for correct gap/actual remaining anode material.