Okay so this happed a few months back and truck has been sitting ever since. Went to drive to a buddies place and on the way there the trans was shifting a little out of the ordinary (shifting hard & slipping) and it hasn’t had that issue before. Nothing else happened after that for about 10 miles cruise is set at 60mph and all the sudden tow haul starts to flash and then loss of all forward and reverse. So I killed the truck tried pulling battery terminals, long story short didn’t work.. so I turn back for home and got about 5 miles down the road and does it again. So I had it pulled to a safe spot left it for the night came back to get it and torque converter was locked up still like when I tried putting it in drive to creep up on a trailer it just bogged and instantly killed the engine. Did some research and kinda messing w it and got it to release once tuned back to stock. (Never tuned hot) anyone have an idea what it could be or where I can start???