Oldsmobile/Buick Repair: engine ?????, hot van, couple seconds

Question
1988 3/4 ton cargo van. took to dealership could not help us. when van gets hot it will turn off. gets cool turns on!!! we have changed many things to no avail. bored catalitic converter changed distributer computer  checked many sensors changed we need help!!!!dealership does not have a way to check our van nor a mechanic old enough to remember how to work on it.

Answer
Hello George,
I assume you have checked for spark when it is hot. I also assume, since so much work was done, that there IS spark when it is hot, so I won't even talk about electronic items concerning spark.
I am thinking fuel.
Has anyone checked the fuel pressure?
That would be a throttle body system, so it should have 13 PSI of fuel at the throttle body, whenever it is running or cranking.
It needs to be liquid fuel, not vapor. I am thinking the fuel lines may be getting too hot, and boiling the gas inside the lines, and acting like a spring.
With a pressure tester connected, you could bleed off some fuel, and see if it is vaporized. If so, you may have an overheating problem with the engine, or a real weak fuel pump, not circulating enough fuel to keep cool fuel in the lines.

It is also possible that something in the fuel pump operating circuit is getting overheated, and causing power to the pump to be lost.

Possible also that the fuel pump just quits when it gets hot. Can you hear it run for a couple seconds when you turn the key to run, both when cold, and then when hot?

Van