98 monte carlo fuel problem

I have a 98 monte carlo that recently stopped running while i was driving it. I had been driving for about 10 minutes when the RPMs dropped and the engine shut off. I turned the key to run and did not hear the fuel pump doing its priming cycle.
I switched the fuel pump relay with the AC relay(they are the same) and checked to make sure that there was power to pump. I pulled the tank and removed the fuel pump which worked fine when 12 volts was applied to it. I changed out the fuel filter and put the tank back up. I hooked up a guage to the fuel rail and it showed 47psi of fuel pressure.
The car started and ran just fine. I then drove it and after 10 or 15 minutes it again shut off and there was no fuel getting to the engine which turn over strongly but did not catch and start.
I came back several hours later and the pump would prime again(4times) and i started the car a couple times but after a bit the pump stopped working. I am still guessing the fuel pump is bad, just doing so intermittently.
When the pump builds up full pressure the car runs very well with no missing or anything like that. After it heats up, and i am guessing the pump too, the engine is starved of fuel and it dies. Are there any other possibilities before I go and spend $3-400 on a new pump that anybody can dream up?

Welcome to AF, sounds like the pump, but check for 12v prime voltrage when it won't start to be sure.

sounds like you may also have debris in the tank that after a short time of suction ( running and driving ) it get sucked up and clogs the pump screen .
Have you noticed any gunk when you removed the pump the last time ?