1995 GMC Sierra van shuts off

When the problem occurs, have a helper crank it, while you visuall check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. Try not to get gas on a hot engine. If your still fully obd1 compliant, you can check your own trouble codes.

To check for spark at the plugs, you can carry a known good plug or spark tester in the glove box. Pull spark plug wire, if hot, the autostore sells a plug wire puller. Stick the plug/tester in the spark plug boot, ground metal part of tester to metal part of engine, watch for spark, engine cranking. Intermittent issues are a hassle, something usually fails when there is nobody around to crank the vehicle, while you do testing, that's the way it goes?