This may sound like a silly question, but have you cleaned all of the bugs out of your A/C condensor and/or your radiator. I had the same symptoms you are describing with my 1991 Chevy truck when I lived in Stephenville, TX. It seems like the spring and early fall are bad times for bugs building up and blocking the airflow through your radiator. Since this has been a wet year, the bugs are probably worse.
