Lost power on 2005 h2
 

I have a 2005 h2 with 53k miles. Truck drove great since I got it 3 yes ago but 3 weeks ago it felt like the truck lost power. Now to go same speed as before I have to press down on gas more. And because of this the engine is louder and rpms get over 2k rpms to get to 40mph then of course it shifts and rpms gets down under 2k rpms. I took it in to hummer dealer and took mechanic for a ride. He connected his diag tool and no error codes came up. He said truck rides like it should. I know darn well it's not driving like it used to. Other symptoms: truck slows down quicker now, truck has no pickup, even if your at 40mph and press gas, it seems like it's struggling to get to 60mph.

I changed the mass air input sensor but still same thing. Truck just doest have the power it used to have and I must press gas pedal down much further now and engine much louder now. Truck has 54k miles on it and it judged this about 6 weeks ago. Going from 40mph to 60mph by just pressing gas pedal down a little bit it gets up to 2500 rpms. Not normal for my truck.

Any help would greatly be appreciated.

Check if you accidentally changed your 4x4 settings to 4L mode.

That sounds like your catylatic convertor might be getting plugged up.

That's what the tech thought also but they ran a pressure test and they said its well within specs. Let me ask you something, if the catalytic converter is clogged or broken, would you feel vibration in gas pedal and also on floor on both sides of front seats? That's what I'm feeling.

Thanks for your input.

Air filter. Or you bumped the 4x switch like Manso mentioned.

Fuel filter

Jack up the truck and check your front and rear differentials. Make sure they have fluid, don't leak and they can spin. Check the brakes, make sure the calipers are releasing. A bad wheel bearing can also create significant drag so check those.
You could do a quick check by getting up to speed and then putting the tranny in neutral. See if you still feel the drag.

front and rear diff
 

I am changing my front and rear diff fluid on thursday and I will see if it makes a difference. I also feel vibration in gas pedal, I feel it at different speeds but always at 40mph, sometimes at 30 and 45-50mph also. Dealer checked the cats and said they are well within specs. I did change the maf but no change. could it be the torque converter? Maybe a full trans flush (lines included) might fix this issue?

I had a 96 crown victoria which bucked bet 30-45mph and the trans flush fixed it, not sure if the vibration in gas pedal is equivalent to the bucking in the Ford.

I took truck for long ride yesterday and concentrated on the vibration. It was doing it bet 20-55mph. If I put it on cruise and place my foot on pedal I still felt it but not as bad as when accelerating. I did not change the fuel filter yet but u should because I am changing my side steps and the fuel filter is right there. Could be the exhaust? Trans? Torque converter?

I occasionally had issues where the truck felt like it was dragging. It would pull slightly to one side. Figured out what it was one night driving. No street lights at a stop sign. I could see the ground glowing in the passenger side mirror. Got out and the entire pass rear rotor was glowing bright red. Literally enough to light up the ground, you could feel the heat 3' away. Damn thing wouldn't do it all the time, but enough to piss me off. Changed out the capliper, rotor, pads and replaced the axle seals just to be safe.