Car dies sharply as if the key is shut off but starts right up. Dies at idle, hasn't died while driving yet. Has new fuel pump and filter. The engine temp has gone to hot recentlybut has not boiled over . New thermo stat put in and had a slow leak according to mechanic.Car has small blockv-8 and auto and runs fine except for this.Any help as where to look for help diagnosing. I'm thinking a relay or solenoid is cutting out and shutting the fuel or ignition off ,but the start right up thing is making it hard to diagnose.

 

I'm dealing with a very simular situation as you are. my post on here
about my 1994 Caprice LS stalling when I drive out of the blue.
If you or I find a reason and a fix we should let each other know.