Tranny randomly downshifts when in OD
 

I have an 03 3rd Gen Cummins with a 47RE tranny that was rebuilt around 160k miles. It now has 220k miles and I have only pulled a few trailers since the rebuild and they were never heavily loaded trailers. So when I am traveling anywhere between 70 and 75 mph the tranny will downshift at random times, and not just one gear or out of the OD but multiple gears, it will drop 2 maybe even 3 gears, my rpms will jump from 2,000 to 3,200 which is right at Redline. It just started about 6 months ago but has gotten worse, almost on a daily basis.
I have taken it to a transmission shop and they couldn't figure out the problem, so they decided to rebuild the Valvebody and replace the OD/TCC Solenoid. This hasn't fixed it, now it downshifts at 55mph which isn't as violent but it continues to downshift at the 70-75 mph range as well.

Any suggestions or ideas/ has anyone else experienced these problems, how did you fix it? Any advice will help, appreciate it!


-TP