I experienced the same thing as you, and I'm in Texas. For me only starts overheating when the A/C is turned on either of the last 2 marks (high and super high, I call them). I've replaced the thermostat, radiator, radiator cap, run Water Wetter, put a fan in *front* of the radiator (along w/the the Voyager fan), pulled that entire setup out and put the high flow VX radiator fan and shroud on, completely removed the hood as well.....no results. Only thing I haven't done is the fan clutch, which I'll be doing as I swap out the drive train.