1997 Chevy Blazer Acceleration problem

I have a 1997 Chevy S-10 Blazer with the 4.3 liter engine. For the past few weeks it would run fine then suddenly just stop accelerating, especially to full throttle. You can shut the vehicle off and restart and the problem straightens out for a while. I read the codes and all codes point to a fuel related problem. The idle air control vacuum line was weak and collapsing so I replaced it, I check throttle position sensor, fuel pressure regulator, wiring harness and all other vacuum lines and electrical connections and replaced fuel filter. My fuel pump works and I have fuel delivery to the rail but am not sure if the pressure is correct. I don't have a pressure tester so I know the pump could be weak. My thoughts are that if the pump was weak it would not run good at times. Also there are issues with the ground wire to the fuel pump on this model, but if it loses ground the pump shouldn't work at all should it? The vehicle has gotten worse today. When you first start it it runs fine but after driving for a short while it will only take the fuel on a light acceleration, too much pedal and it just bogs down, ease up on the pedal and it runs fine. But the longer it runs the worse it gets. I have no problem changing the fuel pump but I hate to spend $300.00 and still have a problem. Any help or suggestions will be greatly appreciated. Also I have removed the catalytic convertor and checked evap system.