Handicap Van dies, will not start, sits for 20 minutes and then will restart

I recently bought a 1990 Dodge Ram 350 Handicap Van with Braun lift to get my Father in his wheelchair out and about. The problem is that it just dies / cuts off. After 20 minutes or so, sometimes an hour, it starts back up just fine. At first, it was not getting fuel to the ignition point. Found the Computer module that was slagged out and replaced it. Started up fine and ran for a while, ( 10 - 20 miles just taking Dad from the nursing Home back to our house for a visit, or to get his hair cut) then it began doing it again. Sometimes it would restart immediately, but usually only after it was towed to the mechanics. Then it start right up and they couldn’t find anything wrong with it. It would sit and idle just fine for them. I would pick it up, and take Dad somewhere during the next week, and it would die again. I would take off the engine cover, check that all the wires were firmly in place, reseat the distributor cap, and then replace the engine cover and it would start and we would continue on our way. Of course all of this would take about 10 minutes or so…The Mechanics are baffled. We have replaced the ignition, the ignition coil, the computer module, the spark plug wires, the coil wires, the distributor and cap, the alternator checks out just fine. It is like there is a sensor relay or switch that overheats and engages and shuts down the engine. We have checked and can find no such sensor on this model. Now during this latest session, We replaced the distributor as we had replaced everything else up to that point. After doing that, it would not start at all. Put the old distributor back in, and still would not start. There was power at the distributor. There is power to the coil. When you turn the key to the on position, there is power, but when you turn the key to start the engine then there is no power to the coil! and it won’t start. Put the new Distributor back in. Now starts and dies immediately. Will restart each time but dies immediately. The Mechanics are tearing their hair out. Any help will be greatly appreciated.

CArolyn

Have them check the Auto Shut-Down relay located on the left inner fender below the 50 pin bulkhead connector.

Tester

We’ve done that. It is working appropriately. Next idea?