2004 F150 Fx4 5.4

On acceleration, everything is perfect from idle to about 2000 rpms. Above 2000 rpms, acceleration and power decreases very noticeably until about 3000 rpms, then returns to normal above 3k. It takes longer than expected to get from 2k to 3k. Almost seems like engine "bogs down" during this period, very noticeable difference in power and sound.

Things I've replaced(whether related or not idk):
fuel filter, air filter, maf sensor, plugs, coils, vct solenoids.

Put an intake on it for about 2 miles, then ripped that thing off as quick as I could. (went on here after and found out that they run lean and '04 model will not automatically adjust)

Had access to use a buddy's edge programmer. Level 1 seemed to maybe help a bit, but still noticed the issue (different shift points/firmness more ideal?). Level 2 w/ 89 in tank didn't make a difference (if anything made it worse). Didn't do level 3. Prefer not to take it to the stealership.

Any ideas or solutions????

 

I would clean the throttle body and see what happens.

 

Bluejay,
Thanks, I'll let you know how it goes.

 

Cleaned throttle body, wasn't too dirty but it helped. Still not 100% or even close. Seems to be doing it more in the afternoon when it's the hottest, not so much when engine or outside is cold (ish).

Any more ideas???

 

What did you ever come up with

 

My 04 F150 V8 5.4L is doing the same thing. What was the fix?

 

I've got an 05 with the same issue. When cold it blows a little smoke and cuts out when you give it any throttle. Heavy gas smell on drivers side but no leaks. Both go away when it warms up but definitely a significant power loss and fuel mileage down the drain. Way more than what would be considered normal. Embarrassed when I have to go up a steep hill. I've watched the pids when it runs good and runs bad and nothing stuck out. Replaced phasers while back with cheap ones. New plugs and coils, air filter is fine, cleaned maf sensor. No obvious vacuum leak but not completely ruled out. Cats are hollowed out. Always a rich code, first on one bank then the other will flag. Possible injector leaking or need to replace phasers again with oem parts? That's all I can think of... I'm out of ideas

 

The 05 5.4 had a bad batch of leaky fuel injectors. Cheap phasers are no good, but I don't think they are causing this particular issue. If replacing the phasers, you should do a full timing job. How many miles on the engine?