Won't go into 5th gear
History: 2008 Job 3 6.4L tuned at 30,000 miles w/ H&S Tuning, has 6" lift and 37" tires. Tranny was great until I installed track bars at 50k miles and since then I have had a minor slip between 4th and 5th gear and it will occasionally shudder when it downshifts.
Present: Today at 66k miles when I accelerated it did the downshift shutter, threw codes and would not shift into 5th or keep the TC locked in 4th. I pulled over and erased the codes (which was stupid) but I believe they were a drive solenoid stuck code, and a slip code. Once I cleared them the truck would still not shift into 5th or keep the TC locked in 4th. I re loaded my tune and still no luck, I'm trying to make this Transmission last another year as I only drive the truck about 10k miles a year.
Any help is appreciated.