Your catalectic converter is going bad. Once it clogs up you will start to see engine temp go up. You need to get it looked at real soon....$300.00 to $450.

 

if the catalytic converter has any more than 1 psi back pressure it will cause misfires on that bank. If a converter is restricted you will see p0300 set and a flashing engine light. Backpressure spec is 0.5 psi for a good converter.

 

With 37's and stock gearing you are putting a lot of stress on the transmission. This is why it won't hold in 4th. It will really shorten the life of your tranny because it's always fip flopping from 3rd to 4th. You could get a Sonnax Super Hold 4th gear servo or beef up the transmission during rebuild(some day) but what really needs to happen is change the gear ratio and increase the horsepower. I think I remember my gear ratio calculations for 37" tires comes out to 4:56 to get you back to the equivalence of stock.
With the increased load (especially at 80 to 90 mph in a steel parachute) you probably cooked and clogged the cats a little.
If you have a knock sensor code the engine will go into some kind of "Safe Mode" to protect itself from the knock. My thought is that many times the code triggers from bad gas or water getting to them not from bad sensors. I've had the code come on and just clear the codes with my computer or disconnect the battery for a little while and you get some of the power back.
Unless your tune is set up for it, 93 octane usually doesn't do much for you. (based on research not experience)
Without proper horsepower to run 37"+ tires or to push these bricks to 80 or 90 mph, we are just slowly destroying and clogging the whole drivetrain.
I run 40" tires, lift, crap packed on a Gobi rack and am somehow always driving into the wind and uphill. I've been through transmissions, gears, cats, etc. I re-geared mine to 4:88. Built my own bulletproof transmission. Auxiliary cooling systems. What I really could use is more power. I say go get that supercharger back.

 

Thank you to everyone who has responded.

Currently having the same issues unfortunately.

I def see a noticeable difference in driveability after filling up with Premium at certain stations. At some gas stations /refuels the truck immediately will throw the knock sensor code P0332 Knock Sensor 2 Circuit Low Bank 2 and the truck becomes a slug... lot of noise at rpms but doesnt wanna move.

Clear the code on the fly and the truck comes back to life for a few minutes before bogging down again.

Definitely thinking about the regear to account for the 37" tires on 22's.

I have a guy coming over today to try and retune the truck on the current ecm and we will see what he is able to come up with datalog wise. Hopefully he can get into it and confirm if it is locked out or not.

He is going to try and do a full custom tune on the engine and tranny and will try to adjust shift points and has told me that worst case scenario if after all that that knock code is the bugger that is still causing the issues he can eliminate it all together.

I believe the Cats were checked and were ok on the truck regarding to the backpressure comments. And have only once had a Misfire Code

MAF - That was the first thing I thought of and the dealer told me it was in tolerance havent changed it yet but what the hell I might anyways to rule it out.

KraBruder… I like your comment "Steel Parachute"
I have referred to it as a brick wall but im going to use that one sometime haha.
Definitely love the truck but need it to be more responsive.
Will let you all know what happens this evening with loading a custom tune ….fingers crossed. If that doesn’t help Going to regear next and retune and see what happens…
Worst Case Scenario dropping a TDSL in there and saying to hell with it lol!

Thanks again to everyone who responded.. Trully appreciate everyone who took the time to do so.