MTH C&O Hudson acting odd...

It might have a bad motor. Do you know how to run the motor on DC without going through the reverse unit?

Are there any rods binding? Can you turn the motor by hand through several revolutions of the drive wheels and there are no spots where it is hard to turn?

Yep! that's good advice. I'd start by  turning the fly-wheel. Maybe even the turn the smoke unit off as well. Something's drawing excessive current. 

While turning the flywheel, I would feel for binding. Had a loco that ran poorly due to improper motor shim clearance excessive play would cause gear bind. I would also try running with out the shell. Sometimes you can see something that is not right.

Thanks for all your advice -- tried it.   The loco part of it runs like a Swiss watch (but need a new traction tire).   I had the top off, and the linkages, motor and other running gear runs very smoothly.  The issues appear to be something in the DCRU.   I suspect it is failing.   I think this would be a good candidate for PS2 conversion....