Pressure regulator question??????

[tps2000]

Hey my 00 Maxima has a problem when I get on the gas pedal. When I get down on it pretty hard the damn thing just stumbles all over itself. I was told it probaly is the fuel pump and then I had someone tell me it could be the pressure regulator. How do I test for the pump or the prssure regulator? If thats not it where else do I turn to find this problem? By the way my Max has 187,000 on the clock.