1992 Chevy S-10 Stalls at idle and doesn't start up right a

My truck will start up right away in the morning, I will drive it to run some errands. Turn it off, start it up works fine but sometimes at a stop light at idle it shutsdown like the key was turned off. It runs great, no hesitation, knocking, etc. I have already changed the fuel filter and fuel pressure regulator diaphragm and spring. Other things I have done, new plugs, wires, distributor cap, pcv valve, cleaned out the throttle body and ran lucas fuel cleaner through the tank. Today it actually did something strange, when it stalled I couldn't get it started this time wihtout using starter fluid and keeping my foor on the gas at a higher idle to keep it running.

Could it be the fuel pump? I hate to take the tank out and replace it if it isn't. Any other suggestions?

Thanks,
Steve