My truck-2005 5.4, 76k miles, champion plugs at 74k miles, flowmaster super 44

Ok, my truck is sluggish under wide open throttle until 35 mph, then it takes off and feels normal. But through 35 mph it feels like its bogging and doesn't have full power. No check engine lights, I replaced the foam seal around the air filter housing, and changed the fuel filter and fpdm. Runs perfect except under wot. Last week I retorqued the plugs and got rid of the fuel smell, but still have poor acceleration.
What could it be? Is it the champion plugs? I put them in because they are one piece, bit looking back I almost wish I had just gone with the motorcrafts and used the antiseize... I really don't wanna throw the $160 plugs away, but its annoying not being able to accelerate as quick as my neighbor who has the same 5.4

Throttle position sensor? Plugged cats?

What do u think?

Oh yeah I also did the throttle trick with depressing the gas pedal.

 

Plugged cats would get worse the higher the RPMs go. Sorry to say but my first step would be to ditch the Champions and get some Motorcraft in there.

 

Well that's a relief! I was also worried more about clogged cats... Thanks for the tip. Anyone else?

 

I agree with VTX. Get motorcraft or autolights. Also clean the throttle body that also might help out

 

Forgot to add I cleaned the throttle body in July along with mass air flow sensor...

 

Nothing wrong with Champions, I've had them in for 40k no problems.

I would clean the MAF sensor and throttle body.

 

I'll try cleaning them again then... I was just reading some posts about champions.. seems hit and miss with them

 

I agree. You want it to run like stock then stick to stock parts. Unless it's an aftermarket exhaust.

 

Bump. Any more opinions?

 

Well after reading that it could be numerous things causing this, I'm not going to throw parts at it. Im just not going floor it anymore I guess. Could be anything from throttle body, cops, plugs, cam phasers, sensors, trans, Injectors, cats or who knows. Oh well.

Oh I did floor it on my way home and I watched the rpms and its in the 3000-4000 range if that narrows it down.. no check engine lights.