just bought this truck and it ran great for a few weeks, was told fuel pump was just replaced and it ran perfect, I drove it one day and it started to have no power it would bog out after half throttle and would take forever to start up it kept getting worse and eventually wont start at all, I ran seafoam in the gas tank and it ran awesome again and even turned over quicker and restore power, now that the seafoam is gone its back to the same problem, thought i would change the fuel filter and looked underneath and there was no fuel filter on the truck so i ended up putting a new fuel filter in. Still having the same problems, does not want to start up it just cranks over, sometimes if it gets started it sounds like it catches a couple times then slowly fires up. any ideas?? thank you

 

Need to do a fuel pressure test to start. If the previous owner was dumb enough to delete the fuel filter I'm not sure I'd trust his pump install.

 

Still sounds like fuel....my 90 350 (I refuse to call it a 5.7) did just that...hard starting and choking under acceleration. Fuel pressure isn't the only thing....flow rate matters as well. Check all of the fuel lines for any leaks that may be allowing air into the system. A new filter fixed mine.