how do i change the fuel pump/

Has someone tested the fuel pressure for you? The fuel system in your truck is extremely sensitive to fuel pressure. If at or below min spec you will certainly experience problems. What your describing leads me to believe your losing pressure at rest. This may be the check valve in the pump or a problem with injector bleed down, or even a leaking line inside the plenum. In other words without proper diagnosis your fuel pump replacement may not fix the problem. To answer your question though, you need to remove or lower the fuel tank to access the fuel pump. Good luck!

I was told that theres not enough pressure coming from the fuel pump.