I can crank the engine cold and it will idle and run perfectly,after it gets to operating temp it shuts off.I can put my foot on the gas pedel and brake to keep the motor runniing as long as I keep the revs over about 1500rpm,then when I drive and the revs fall under about 1500rpm the motor will die even at highway speeds.I've replaced the TPS and IAC,sometimes the motor will surge before dying,I'm guessing that's the IAC trying to keep the engine from stalling.Any ideas where to start tracking down the problem?Thanks in advance for your help,this problem is driving me crazy.The AFR on my wideband goes extremely rich when the engine is trying to stall so I assume that the problem is in the ignition.