My 1993 Buick LeSabre will start, turn over, and immediately will die.

Fuel pressure should, be fine. The reason I say this, is because I went ahead and gave the engine a little gas while holding the brakes and drove my car, after about an hour of driving it (every time my foot left the gas pedal the car would die.)it fixed itself, but obviously it didn't. So right now the problem I am having is either the Car is idling too fast or too slow, but I have recently changed the idol sensor in my car twice. It sounds like I need to change it again. is there something else it could be?

you could try another iac valve,make sure the pintle is not out to far.should be an instruction sheet with a new one.pull the vacuum line off of the fuel pressure regulator,if any signs of fuel in the vacuum hose,replace the regulator,it's bad.