1992 Chevrolet Lumina possible electric wiring problem

The oil pressure gauge pegs out when key is on, sets to 40 psi when engine running. Then after driving 15 - 20 miles, engine shuts down. I coast in neutral to a full stop, sometimes it will restart right away; other times it will take a few tries. During restart attempts, oil pressure gauge ranges from pegged to 0 intermittently. Could this be wiring, ECM, fuel or a combination of these? I have owned this van for 3 years with no issues.