01 xlt seems to running in limp mode

Hi all, My 01 Offroader is at 200K and rolling 33" tires with a rear lift and Move |Bumper.

That being said, two years ago I eliminated the CAT Converters in Indiana for some more horse and added a Volant Cold Air intake. The truck performed fine for several months but returning from MOAB to indiana i started to experience no acceleration in all gears once the pedal was pushed more than a third of the way down.

I have dealt with this for some time but my most recent trip to the rocky mountains required me to stay of major expressways as I lose speed on hills and can barely get the vehicle to drive 60 MPH.

Ive checked air lines, replaced Mass Flow Air sensor but still get lean codes in bank one and two.

I have a ECT monitor for critical info in the vehicle so it shows me the codes.

Here is my question. Where do I look next?
No Visible exhaust leaks.
Air lines and pcv valve seem fine.
Throttle body is good and clean.
Tried resetting with battery as well as programming factory settings.

The transmission shift fine but often I have to feather the pedal in order to get the next gear.

I want to solve this and am hoping someone came across this. My brother who works for Hitachi air flow group says the cat Conv cuts as screwing up the program. I cant believe this as it ran fine for months after my dual exhaust was installed. Please advise.

Come on now fellas. Help me out!!!!

Lean codes usually mean air leak I think, so if you are positive that isn't the problem I would think the next easy thing to rule out is a fuel problem. Maybe verify pressure at the rail and make sure your fuel filter isn't clogged up.

Yes, check fuel pressure it may be low. They say you can borrow a fuel pressure gauge from AutoZone.

On it today. Will update

Okay. Checked the pressure at rail . 33 at idle and almost 50psi at load. I believe this to be oka . Thoughts?

Yeah, that pressures fine. You can eliminate pump, lines, filter, from the equation. I'd check all 4 cats, sounds like one or more is clogged.

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Well there in could be the problem but they were all removed(indiana) no emission testing. It ran fine straight piped for over a year then started suddenly and consistentl . Trans shifts fine but as stated earlier, if i go more than half pedal i would have to feather the pedal back sometimes in order to shift higher gear.

Resetting the pcm through battery drain has not helped.

I know its old and dirty but its my toy and i want to keep it. Problem with offroading is trying to climb a hill when i have little to no performance acceleratio .

Open to other suggestions Pcm check?

The loan code could be from bad o2 sensors and the computer not seeing it but I'd double check there is no intake leak, id spray around the intake with brake cleaner just make sure you do not spray the filter and. Try to avoid electrical the best you can if the rpms increase with the spray there is your problem

Easier than spraying everywhere, smoke the motor through the hose that goes to brake booster. If your a smoker yourself, you can exhale through the hose and look for where it escapes. If not a smoker, a smoke machine is easy. I've never seen a vacuum leak cut totally the horsepower. It will hamper it, but should keep running. Do a fuel trim test, check the 02's, and MAF sensor. I'd also do a voltage sweep reading of the Tps switch. I'm wondering if yanking the Cat's has something to do with this. The vehicle and computers were meant to run with them. Gonna be a fun one to figure out.

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