Big loss of acceleration ,,,I'm stumped!
 

First off let me say, My truck runs and drives in normal conditions, in town traffic with no problems. I normally drive like an old man in an attempt save fuel. LOL The truck is "rarely" ever pushed hard. So, I don't know how long it has been this way.
But recently I put my foot in it and realized at some point something bad has happened.

When I go WOT throttle and it gets to around 2000 rpm it feels like I'm pulling a trailer. No go!
The engine sounds normal and like its pulling hard but it's not accelerating like it used to.
It almost feels like its in a taller gear but its not.

Last weekend I purchased and installed a new throttle body from Ford. I replaced the fuel filter. I cleaned the MAf sensor and cleaned my K&N filter. Neither of which were dirty.

The only MODS that are on the truck are a K&N drop in filter and a Superchips flashpaq tuner. The tuner is currently set on 87 octane performance tune.
The truck used to really pull hard in that setting.

So, what else can cause major acceleration problems but yet throw no codes?

Catts maybe?

I would have the cats checked. How many miles on the plugs? You could be running lean with that intake, that tune on a 2005.

Sounds like plugged cats

I need to have the catts checked. Not sure how that is done. I'm not running an aftermarket intake, its simply a "drop in" K&N filter in the stock airbox.

I replaced the spark plugs at 100K miles. It now has 129K, so I think its good there.

Never had this happen before. Its so crazy because it runs absolutely fine until I want to jump on it.
It then says no! It doesn't bogg or anything, it just doesn't go. LOL

A muffler shop can check the cats.. If they are bad, makes me wonder if you might have injectors that are leaking just a little.

I have a friend that owns a Speed Shop in Dallas Ga. I just talked to him and I'm gonna go by there after work today. He should be able to shed some light on this.

Sounds familiar:

https://www.f150online.com/forums/ex...-loss-fix.html

Yeah, I had already searched these forums and read that thread.
I already checked on that and no foam or obstructions in that area. I was hoping it would be that easy.

I also went by my Friends shop this afternoon and he checked things out for me. My catts are clear.
He is also scratching his head on this. We decided to swap tunes in my tuner to the 93 performance tune just to see how it affected it. It definitely feels more 'ballzy" with that tune versus the 87tune but you can tell its still feels held back.
He also suggested that I run this 93 octane performance tune, 93 octane fuel, and some fuel injection cleaner fuel additive for awhile. And, he said I need to quit driving like an old geezer, drive it harder and "Blow it out". LOL

My fuel system might be dirty and valves might have carbon build up on them because I never drive the truck hard and run cheaper 87 octane fuel.
He said that the higher octane fuel, injector cleaner, along with a "heavier foot" should clean things out on the inside.

I da know, its a theory. LOL

Have you ever had the injectors looked at or serviced? I just had the "scheduled 90k miles injector service" done and I never would've thought about that had the dealer not told me. Don't know if it was worth the $140, but I figured what the hell and did it for the peace of mind.

No I haven't. I bought this truck 2 years ago with 100K miles on it to replace my nearly identical '04 that was unfortunately totalled when a gal decided to pull out in front of me.
I don't know what service had been done before I bought it but it has been a solid performer until recently. I really like the fact that the cam phasers are quiet and not clattering like my '04 did.
At the end my '04 had 155K on it with really bad cam phaser issues.

Just figured I'd ask cause injectors maintenance is more important on the 05 cause of the issues, and not like I'm super knowledgeable or anything, but nothing comes to mind as to what it could be with everything that has been checked and given the OK.

My 06 is pretty quiet compared to ones that get bad, but long tubes headers tick, so it's hard to tell what's phasers and what's LT tick. I think mine are chattering a wee bit, but nothing bad yet. It was silent when I bought it at 74k and it's almost to 92k now. I do remember what happened to your old truck and how you purposefully went and found its brother :lol:

If it's the injectors, run some techron concentrate through it and that should fix it. Injectors should last till the truck dies

I'm running Chevron Techron right now.

Update: Well for the last 3 weeks I've been running 93 octane fuel, injection cleaner, and I loaded the 93 octane performance tune into my computer from my handheld tuner.
It has felt pretty nice and somewhat ballzy under acceleration.

Due to the fact that gas prices had a big jump in the last few days I filled up with 87 and retuned it back down to the 87 tune from my tuner.

TOTAL loss of power again! Once again it idles and drives normal but has no acceleration whatsoever. It'll jump down two gears at WOT throttle trying to go but it feels like I'm pulling a trailer.

I just don't get it.

Since the 93 octane was performing...I think you can reasonably rule out the fuel system since it wouldn't work differently across octanes. Which would leave intake and tuning as the likely culprits. If it were me, I would clean the MAF (maybe the whole intake system up to the TB), put the tune back to stock, and drop in a paper Motorcraft air filter and see what comes of it. Reading your spark plugs wouldn't be a bad idea either.