I have a 1997 Pontiac grand prix gtp that randomly dies while driving down the road. My husband has replaced everything we can think of. Please help

I had a Chevy about that same year do that. Despite the fact that the coil would check good it turned out to be just that.

What parts were changed? If it happens now and then, Look at the ignition module under the coils and the crank sensor. If randomly, go after the crank sensor. Other things could cause this also. What's the engine size?

Has he had a pressure check run on the fuel pump?

Make sure that when it happens again check to see if there are any lite up lights on the dash that were'nt there before indicating that there may be a problem, if so find out what the sysbol means or you can take it into a shop and have them diagnose the problem