98 Mustang stalls in hot weather

99% of the time the car runs perfectly but when I take a long trip in hot, humid weather, it will lose power, and if I keep driving the engine will stall. It only does this in hot, humid weather. When I pull over and shut down the engine just for a minute or two, it will start back up and run fine. At its worst, it will do this every 20 miles or so but it can go as much as 50 miles. The problem has occurred only once after sundown after driving 200 miles without a problem then idling for several minutes.

i had this problem to myself i changed the thermostat and flushed the system and my car has not done it again