Alright, 04 5.4L 4WD yada yada.
I've noticed over the past few days the trans has been lagging when i punch it to merge into traffic it boggs, then slowly climbs, then goes faster as it climbs. Trans was rebuilt at 71k, it now has 113k on it. I do tow a horse trailer about once a week with it, but never had any issues with that ( I always turn off overdrive when towing, btw). I figured it had been a while so I went ahead and cleaned the throttle body and MAF sensor tonight just incase that was the issue. Still didnt fix it. Throttle response is good in park just seems to lag in gear.

*I also had a new fuel pump, new spark plugs, and new fuel pump driver module replaced at about 90K.

Now, I checked the trans fluid, transfer case, etc. Any other ideas what could be doing this? It seems like when it boggs, I can really hear my K&N air filter making that bogg sound. It does tick really loud more recently then it has, which I suspect before was just the cam phasers. I'm not sure, it may be coming from the trans though.

Any and all help is greatly appreciated

 

Had the same issue... mine turned out to be a clogged Cat from two cylinder misfires. Couldn't hurt to check into that. Never threw a code for the cat as well....

 

Could be FPDM as well...

 

I mentioned above FPDM was replaced already. But thanks, how do you check for clogged cats. Never thought about doing that and never replaced an 02 sensor yet either on that truck.

 

well it depends on how bad it is... I was able to tap on each cat and noticed one had a rattling inside of it, and i heard the rattling/cracking under WOT. Thats when I took it to a shop and just told them to replace both cats. Sure enough, the rattling one was clogged to hell and back. Sorry didn't see your mention of the FPDM.