The truck is an 03 auto, the transmission was rebuilt about two years ago with a shift kit.
the problem is that the truck will shift out of 4th to 3rd intermittently while going straight and everytime while turning to the left, it will not do it at all if I turn to the right.
Repairs I've made so far are..... New alternator, new speed sensor, new gov pressure soleniod and sensor, new over driver switch, adjusted the bands, cleaned all the grounds and even put new battery post connectors and tin foiled a bunch of stuff.

The problem started shortly after my flywheel came apart, after the repair I pulled my camper home just fine. After unhooking the camper it started.

I live in Tennessee and had to leave for a job in lowsyanna, I decided to hook the camper up and just take it slow but it did fine until Shreveport, when I'd take off from a red light it would shift 1 2 then to lockup. I stopped and tinkered with it a bit and took off, it was fine after that.
I finished the trip to baton rouge with no other issues.
I worked down there for two weeks driving the truck and it did fine, I towed the camper to Arkansas and as soon as I unhooked it, the truck started down shifting from 4th again.
I tried hooking the camper up since then and it'll do it with it on now.

It does it from 45 mph to 65 mph, anything over 65 and it'll stay in gear. It's not slipping just down shifting. Any thoughts will be welcome, it's frustrating to say the least. Lol

 

Sounds like your torque converter is letting loose at that mid rang speed. Shift kit was done and not converter during the rebuild?

 

Yeah it got a new converter, not anything special just a stocker.

 

Okay so today we put new injectors in the truck, the 4x4 now works and the shifting thing went away, but I now get a p2149 (injector circiut) and the truck will randomly just sputter like some of the injectors cut out. It died once on the highway as well. I'm gonna pull the programmer off in the morning and start there.

 

I found thishttps://www.obd-codes.com/p2149