Will not go bogging down

I have a 1999 yukon denali, It Runs ok in my driveway until I push the gas, when i am driving it no matter how hard i push the gas it goes very slow like 15mph I have replace the O2 sensor, the fuel pump, fuel filter, the mass air flow sensor and and fuses. I dont have a cule what is wronge with it i have replace all these things in it because i was told that that is what was wronge with it now some one is telling me that it is the fuel pump again but i put a new one in it and it was doing the same thing nothing i do to it fixes the problem. I dont know anything about cars should i have some one replace the fuel pump again im tired of my truck sitting in the drive way like it has for the past 6 months. i also wanted to know how much fuel pressure it is supposed to have i want to check that before i buy a pump.