ok, i have 5.4 in a 1998. starts fine, the trouble start is while im driving, it will act like it has a misfire but no (cel). it doesnt do it all the time. truck will run normal for a couple of days then start acting up. im also going through gas like crazy. im thinking its the sending unit in the pump. i replaced all the plugs and coil packs. new fuel filter and gas tank. the fuel pump is the only thing i havent changed yet. any thoughts r welcomed

 

Fuel pump won't cause that. Try some Techron in the gas, you may have dirty injectors.

What brand plugs and coils did you use?

 

I used motorcraft pluges and coils. I also put some sea foam in the gas

 

As stated above, use Techron, not sea foam.

 

Explain how it's acting like it's a misfire. What's it doing at what speed?

 

it happens at any speed. it acts like your running out of gas. i noticed something today when i put gas in my truck. i only put in 3 gallons when low fuel light came on. the needle went up to half tank. then went about 15 miles. turn truck off. turn truck back on gas gauge went to 1/4 tank. went to my next stop. turn truck off. got back into truck, gas gauge went to 3/8. go on the highway ran fine all the wat up 70 mph. slowed down a little bit, tried to get on the gas it started to sputter. left off gas and slowgot back on the gas ran fine.

 

I second the dirty injector theory first and foremost. Give it a good rev in neutral and see if it winds up ok. Highly doubt fuel pump but its possible. And just because the CEL doesnt illuminate doesnt mean there isnt a code....what if the light burnt out??? Have it scanned for codes just to be safe and do what GLC said and put a good cleaner in it!