Well, it doesn't have TPS so that is out. If Texas(tx) really makes it shift bad then just leave and see what happens. :-laf
Not sure from the description what shifting problems you have under 20 mph but if it the usual it is shuttle shifting between 1 and 2 under light throttle. To clarify, shuttle shift is the transmissions inability to figure out what gear it wants at a given time.
Since your out of warranty getting the dealer to fix it probably a lost cause because they would put the same old crappy parts back in it so you need to source some parts that actually work most of the time and stay working longer that the typical OE ones.
Call Sun Coast Diesel Transmissions and request 1
Dodge 618 Upgrade Governor Pressure Solenoid Kit and 1
Governor Pressure Transducer. The Suncoast transdcuers seem to be a better piece than available elsewhere and the solenoid upgrade is the same as you can get other places. You could probably save yourself $10-15 on Ebay if so desired. The upgraded solenoid looks like the attached pic.
If that doesn't work to your satisfaction do this:
Remove the TTVA motor.
Remove lower cover - Metal cover that is clamped with metal tangs.
Remove cover carefully so the gears do not fall out.
If you turn the shaft counterclockwise, looking at the actuator up side down, it can result in codes 1751 and 1754.
Adjusted the shaft one tooth CLOCKWISE.
If you still have shuttle shift you will have to dig into the VB, servos, accumulator, etc, to find where the problem is. A shift kit and billet verions of the previous is not a bad idea either and will definitely help with flaky shifting. However, the 2 things above are rlatively easy and usually fix the problem.
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