68rfe automatic tranny /2008 dodge 2500 not shifting past 4th

so my 2008 dodge ram 2500 diesel started acting up with p0734 incorrect 4th gear ratio DTC. i wasnt driving it when it happened so i’m at a loss. when i first drove it when it happened, it shifted perfectly fine from 1st-3rd, but when it went to shift into 4th gear it’s like it loses everything, (power, speed, everything) and it stays in 4th until i $@$* it off and restart it. So doing the research on the code it was also throwing my range sensor code too. So i started researching everything and started troubleshooting. I’ve changed my shift solenoid, my valve body, input and output speed sensors, my transmission oil pressure sensor, my fluid and filters, all the wiring and connectors going from my pcm and tcm to all these sensors, my batteries and even bought a clutch module n pump plate which i haven’t changed yet. But after doing all these changes, the code for my range sensor went away but the code for incorrect 4th ratio popped up along with the code for TCM ( MIL REQUEST). now as i said, my truck starts up and runs fine at an idle, i can shift from park to reverse, fine and the truck goes in reverse, and then from there into OD or i can put in manual mode with the -/+ button on my shifter. Now i can do it manually just fine from 1-3 and everything shifts fine and runs fine , and i can even downshift from 3 rd -1st and back through all the way to park. the only issue is when the truck shifts from 3rd-4th either way i lose any go or shifting of any kind and when i try to gas it it just revs up and does nothing. Now if i’m in manual the 4 pops up and it stays there until i come to a stop , kill the truck and restart it. ANd then it does everything fine until i hit 4th gear again. i’m at a loss here and i’m tired of paying for parts that don’t fix the problem at all . I’m also not financially fit to send it into a shop for them to charge me a buttload of money . Can someone please tell me what to do or help me single out a fix for this thing cause i’m losing my mind.