from the new statement i bet it's a pump .

Just put a new pump/filter in and call it a day. Only thing that worries me is whether or not the old tank had rust in it and how much rust got to the rest of the fuel system.

 

those are notorious for a huge vacuum leak at the throttle body. its a big hose that goes from the throttle body to the right valve cover. sometimes the hole will close itself and sometimes it will stay open .Do you hear any vacuum leaks? its the first thing I look for when an expedition or any 5.4 comes in in running bad.

ps ..I didnt read all the other posts so I could be off base. Dont have time to read some those books lol

 

been working late all week im going to work on it this weekend, and try all your guys advise, thank you and will update, so if someone else ever has this problem.

 

did you solve the problem? i have exactly the same problem on my 1999 superduty f 250 5.4 triton... i replaced the fuel pump, fuel filter, tps, fuel regulator...

please let me know.. regards

 

fuel pump/ fuel filter, these trucks are rock freakin' solid my old 97 had 250K on it, towing a race car, I replaced the fuel pump at 125K the timing chains at 110K and 220K. other than the filters, plugs every 100K and the TPS switch, I've never touched it.
Good luck with it.

 

thanks, i bought a new OEM fuel pump and i will install it tomorrow

 

One more thing to look at, behind the battery, there is a vacuum canister that is square in shape, remove the battery and take a long look at that.