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.

egr valve maybe....
do you have any service records?

how does the fuel pump sound? strong or week?

Check the fuel pressure. Could be a bad fuel filter or fuel pump. If those are good, then check for spark.

Guys.. let'* also link in the ground buss. The one on the driverside has been known to cause this.

huh...good point Bill

https://www.gmforum.com/showthread.p...ht=ground+buss

What we need to ask is, does the engine cut out like it was turned off, or does it sputter a bit and then die? A fast cut out would point to electrical, a sputter then die points to fuel

It cuts off like you turned the car off.