Typical GM transmission problems rant/questions

[Zayne Snyder]

Hey guys, I have a 2014 GMC Sierra with the 6.2l and a 6l80e. Backstory, some stuff has been done to the truck by the second to last owner to tune it up fairly hot about 415WHP and I ended up buying the truck private from a kid. Just prior to me buying it the kid managed to do a pretty good burnout cause he not only smoked the tires but it smoked the 3200 stall TC to the point the truck didn't move period and turned the rear end into oatmeal in one go. He then sent it to a shop to fix it with stock counterparts (TC/Rear End - Trans was not rebuilt or replaced to my knowledge), so he said. Now the shop that I'm not a fan of and ill explain, not only cut $700 headers in half with a sawzall (which unbolt halfway down for trans removal) then proceeded to weld it back together with a bachelors degree in the art of Swiss cheese. What really confused me and made me loose faith in them is they knowingly put a bent ring gear back in the truck in the hopes "It might straighten out" (literally what they said and I can confirm it didn't). Anyway were here for the transmission which they worked on as well and needless to say the trans acted funny when I got it so I figured the it was the trans tune for the 3200 stall converter not agreeing with the stock tc. I brought it to a tuner where he tuned in the stock converter which helped a little bit for about 9 months. None the less I'm having more problems now, my fluid is still red and I run about 120-135 trans temp normally but I am starting to slip occasionally and I hear a noise similar to bad power steering pump at idle. I also surge a little like a weak misfire when going uphills unless I downshift and go over 2,000 rpms. No misfires on live data and fuel psi is all good. Thanks for reading my rant and does anyone have any Idea on what I might be looking at here? Stumped me for a few months now and it honestly makes the truck almost unenjoyable to drive.

 

TDLR: Transmission works exactly as GM intended; just well enough to get you to the dealership for the all new GM with "2 more gears, see you in 2 years"