2001 Ford Focus stalling when weather gets over 85

Engine Performance problem
2001 Ford Focus 4 cyl Two Wheel Drive Automatic 100k miles

2001 ford focus thats no dealer can seem to fix 3 different dealers and no problem found runs fine all year until the weather gets 85 or so and the humidity gets to high then I can drive it maybe an hour, then its starts off like this hesitation, after a few more miles its begins to get worse, meaning you cant hardly step on the gas, cant get up small hills, then check engine light comes on blinks for abit light goes solid car stall shuts off, at that point its usless to try to start it again for atleast 20 minutes couse it only turns over, after the 20 mintues or so it will start again and run rough, but only for like another 20 minutes then im back to stalling again, take into acount it only does this when the weather gets to warm out, im thinking something is over heating and shutting down, any ideas?The car temp never moves ford gives me same story they can replace 1500$worth of crap but doesnt mean the problems fixed, maybe 4 times a year this affects me but its time to try to get it fixed not live with it please any ideas would be great thanks