95 Explorer Chronic Code 628 w/ Flashing O/D

I've had the transmission replaced and after 12 months the problem is
back. I believe the the previous owner had it replaced once also.

I'm now in the habit of resetting the computer (disconnecting the
battery or reseting it with the code reader).

Are there external sensors that would cause this that can be replaced.
Or is there a modified Power Control Module that won't lock in the
code and cause the limp mode.

I'd put a piece of black over the flashing O/D light, but the limp
mode (clunks when shifting to first at a stop) that's driving me
crazy.

I just don't want to be changing the transmisson every year to get
relief.