Engine Mechanical problem
1999 Pontiac Grand Prix 78,000 miles

My car stalled and died when driving down the road. When try to restart it will start idle rough for couple seconds and die again can hear the fuel pump running when turn the key to the on position and put new fuel filter on the car as well. Car still will not stay started is it the Fuel pump

Have the fuel pressure tested with a mechanical gauge, if above 40psi, then the FP is not the problem.
It could be a bad coil pack or ignition module.

I, too, had a problem similar to yours. I tested my fuel pressures, tried to retrieve any codes, etc., changed fuel filter, disconnected battery for a while...everything seemed normal. I had a friend who had a fuel injector test kit. I unplugged one of the wire connectors on the injector and plugged the test light in. When my wife cranked the car over it started. We shut it off, hooked up the connector to the injector again, started it up and it's been running great for the last 80k miles...go figure...