Truck Forums - Fuel Pump Issues?

Hi everyone!
I am looking for help. My dads 1996 chev with a 4.3 v6 doesn't always start. Usually I have to dump gas down the throttle body and then she fires right up, and runs just fine no stumbles or hesitation even under full throttle. I have just done some pressure testing and now I am even more confused. Usually it won't make more than 54psi key on engine not running. At 54psi it won't start. Sometimes it won't even make that and other times if you keep cycling the key it will make 62psi which is enough to start engine. Sometimes it won't come above 0 on the guage but the pump is running. Sometimes the pump won't even come on. When I can get the engine started it idles at 54psi on the gauge. Rev it up and the psi goes up then down and holds steady. Sometimes when you shut the truck off the gauge will hold any where from 54-62 psi,usually it creeps up from 54psi to 62 psi, other times the pressure just drops to 0 instantly. The fuel pump was replaced 2 1/2 years ago, fuel filter was replaced 2 days ago as I thought that was the problem. The truck has 323000 kms on it but the engine runs very well doesn't even burn oil! I am thinking that the problem might be the fuel pressure regulator? Or should I change the pump? Fuel pump relay is good. Any thoughts? I don't want to put a 4-500 hundred dollar pump in if thats not the problem.
Thanx!