Leonidas Ureña Echeverr&#23

Hello, I have a 2001 suburban V8 5.3, engine hesitates a lot, dies on me on the road, starts back up but very weak. We just did a tune up and fuel filter change thinking that could be the issue but it actually got worse. I checked the fuel pressure and it is 20psi with the ignition on and 23 psi with the car running. I changed the fuel pressure regulator and the fuel pressure regulator vacuum hose (which has been discontinued by gm awful move), the problem still happens and the pressure is still the same.. There is no gas smell anywhere other than when the engine starts and it is hesitating, no black smoke. The only hose that I know it has a leak is the fuel intake hose from the gas cap to the gas tank... would that make the pressure drop that low? any ideas what could be causing the problem?