2000 Chevy Lumina Only A Pro Will Know!

Yes, this is one of those hard questions that probably only a real pro will have an answer for. Let me describe as briefly as possible:

1. Car cranks ok cold. At about 2k RPM's, engine hesitates, chokes, or acts up a little. Unable to floor the accelerator as car will bog down and tach flip flops up and down wildly at times, then car dies if given too much gas.

2. When car reaches a high temp of 180 a summertime only temp, car will die unless being driven. At that temp, when car dies, it is nearly impossible to restart until it cools. At this point, trying to start the car causes severe misfiring and backfiring in engine / manifold area until car cools.

REPAIRS DONE SO FAR: I have overheated two starters and replaced them. I thought it was a fuel filter issue, but that has been replaced and no effect whatsoever was made. HOWEVER, when I use STP Carb and Injector cleaner, two bottles per 1/4th tank of gas, car runs fairly well, but not perfectly.

HOW DID THIS ALL BEGIN? I drove through a 6 inch puddle of water one day, and was doing probably 30 mph when I hit it. The car was slowed by the impact of the water. In just a moment after the impact, the car was very hard to start and keep running. And has had this prob since.

I know this is odd stuff but Im at a loss and the car is vital to my work.

Thanks for your help!