2004 chrysler sebring overheating?

[Wanda]

I have a 2004 Chrysler sebring with 92k and I really want to run it off the side of a cliff, but i still owe too much money on it. the car was not heating properly, the heat would come on, but when I stopped at a light, it would blow cold air. so i took it to a mechanic who replaced the thermostat. then the car started overheating. i took it back to him and he said that the water pump needed replacing and it would cost $1400. I said thank you and picked it up. another mechanic told me to turn the heat and fan full blast (as did the manual) until i could get it to a shop i did and it would not overheat, but i could not drive it for long distances. i called around and got estimates for $700 and $600 (almost 1/2 of what the 1st mechanic would charge). i decided to take it to the mechanic i had been dealing with. he replaced the water pump, tested it and it worked ok. but then the car shut off and would not start. they said it was the computer, so they ordered a computer and placed it in, had it reprogrammed and it worked fine. they took it out to test drive it again and guess what it still overheated! This has been going on since the end of November and I am at my wit's end. Any suggestions???