I would like to get some of my mileage back at 78 miles of babying my truck and trying keep it under 1500 rpm I've burned up half a tank

 

With your inability to accurately describe what is gong on, what has been done to the truck and bringing in modifications trying to clear an issue; there is no help to offer until you do because what you are saying makes no sense.
I can't be anymore clear.
If you want to start from the beginning,
tell what has been done to the motor for changes, what replacement parts have been installed, what codes might be present and or any other info that would be helpful.
Any transmission work etc.
.
To remind you, being in 4wd H is no different than in 2wd for transmission shifting. Nothing changes but the front axle linkup and drive through the transfer case.
In 4wd L there is an automatic shift change that takes place. Are you in 4L when you see the difference?
Saying shifting is different in 4wd H is not very possible so you need to clear that up.
If there is no meaningful information exchange, there is no help.
We will try as long as you will reconsider how you respond.
Super chargers and trans shift kits are not part of your present issue so leave those kinds of replies out.
Good luck.

 

I had put some Lucas transmission fix in it and drove it around 3000 miles since now it down shifts alot better in 2 wheel drive but it does not have any power unless I give it enough gas to make it shift down if I'm at 1500 rpm It jumps to 1900 or it wants to go straight to around 4500 rpms but there is no power if if I try to speed up the road has to be perfectly flat or I have to make it down shift to stay at the same speed even I know it is time to change my wheel bearings but that should not make me have to down shift to keep momentum I hope that's enough explanation for you

 

You keep bringing up new things you did.
Leave wheel bearings out of it, it's not the problem.
Is there any codes set by reading from the data jack under the dash using a reader or scanner?
Is the OD lamp on or flashes?


If your not able to address the issues you need the services of a good shop to sort it out without your input.
Or are you fooling around faking it?
Good luck, i'm done.

 

I haven't plugged it in no light is on my engine light was flashing about a month ago

 

No transmission work that I know of I bought it with 180,000 it now has 194,000

 

OK if I have deciphered this correctly it sounds like an engine issue, not a trans.

symptoms, lack of power, causes driver to force downshift to maintain speed. You have no error codes flashing currently, but one month ago you did have a check engine light.

I would have some one with a code reader pull any old codes that exist.

 

Sorry pulling up yor post kinda old but had a thought on it . So in my opinion after reading it again , I would have the same issues n the kit did help but I'd say that having larger tires maybe some miles n 3.55 ?gears n computer keeping under rev limiter ,with power band . Your lookin in my thoughts , more power gears n program.
I had a programmer that let me set the shift down rpms . But u should almost b driving manually when playing in mud to avoid constant up n down shifting.
Remember these trucks were mad for granny to us driving I don't think anythings wrong .just some personal tunes n add ons .