I brought a 94 bonneville. This car is a mystery to me and the mechanic it cranks and runs but cuts off . The guy has changed the crankshaft, but it is still doing the same thing. Any suggestions to what it might be? Also not showing any codes, someone please help.
It cuts off like you turned the car off. ((( (Sorry about the double post but this car has been at the mechanic for 3 weeks now and no one has a clue what to do))).

Does it cut off like someone turned the switch off? If so, it'* electrical. Or does it sound like its starving for fuel and stumbles a tad bit and shuts off.

Considering the age of your car, I'd suggest looking at the ground bus on the drivers side.
https://www.gmforum.com/showthread.php?t=278980