Has new knock sensor...new computer...new distributer cap snd rotor...new ignition coil...but still no spark

Truck will drive and when stopped at light, engine turns off with some warning lights and loss of power. Will not restart or generate error code to trace. Truck then needs to sit for 60_90 minutes before starting. This is a major safety hazard. Chevy isn’t able to resolve.

After the dealership replaced the sending unit in the truck the gas gage started reading full or empty nothing in between and sometimes it will throw a check engine code. Would the be in the fuel pump or would that be a problem with the computer I’m really looking for a place to start. Is there a place that i could run a meter to see what the problem is before i start tarring into things?