I have a 2000 chevy with a 5.3 in her. I have put 2 fuel pumps in it. Not the problem. I put a Delphi in it the last time. I have changed the Fuel pressure regulator and fuel filter. OK heres what its doing. When I start it in the morning or after sitting shut off for as little as 5 minutes, or all night it will start right up, however if you try to take off, and its a pull on the motor like going up a hill or to get on it in traffic, if falls all over itself and will hesitate for 10-15 seconds, then all of a sudden snap out of it and take off and not do it again til I shut it off again. If I let it run for 2 minutes before I take off, it will be fine. It acts like it is losing prime ??? HELP Please. I would like to sell the truck but need this fixed first. Other than that, its quiet in the morning when I start it up then starts to knock a bit, everyone says that's just the 5.3 but I think it has a couple soft lifters in her. Thanks for the help!!