After working over 25 years in a big car barn my thinking is that your friend needs to find a place that specializes in electrical problems and give them a call.
Try using your puter to find someone to call as you might have to look many miles away from your mountain top home.
Could be something as simple as a broken wire that lays in the correct place when off and starting but when it starts running vibration causes a loss of continuity and the engine DIES.
Try looking on the u tube pages as it could be a common problem with his year and model vehicle and a simple .10 part can fix the vehicle.