1987 Chevy Celebrity - Keeps stalling Out

I have a 1987 Chevy Celebrity w/a 2.5l automatic engine. Physically its in really good shape and only has 64k original miles. Consistent issue is it will crank (sometimes very hard to get it to do so, then run smooth, sometimes for days, sometimes for only minutes, then stall out. It usually stalls after the engine is good and warm. If you let it sit for about 5-10 minutes, it will restart and idle smooth and then go into stalling out again, sometimes within minutes, sometimes days. I have replaced the fuel tank, fuel filter, sending unit/fuel pump, fuel injector, throttle body, the computer, exaust/muffler, mass air flow sensor, several other sensors and it has not improved or worsened the problem. I have sunk $1700.00 into this car in replacement parts. I can’t believe that there’s much else left that could be the cause, and I suspect its bound to be something simple, like a sensor or something, because pretty much all of the expensive stuff’s been replaced. Any ideas?

When it does this has fuel pressure been checked? It could be the fuel pump relay. Crank position sensor if there is no spark.