OK guys, let me tell youwhat is going on. My car surges at idle when it has ran for more then thirty mins and has sat in traffic. IT is not a miss, just a surge. It only happen at idle, but had a hint of it a 1500 rpm the other day. It goes through all the gears smoothly up right up redline. So far i have replace the IAT and IAC motor. After i replaced the IAC it got better, but then came back, just not as bad. Oh yeah, my waterpump weephole is not leaking, so opti is very unlikely IMO. 55k miles on car.

I know this is a heat related problem. I really becomes present