harness plug getting hot

The factory added a little piece of wire about 5 inches with ring terminal on each end.
It went from one steering column to bracket bolt to one steering column support bolt.
All it does is insure column ground for the horn and the shift indicater lamp. The main reason it was added is because without it the ground path was through the bearing.
That ground jumper has no effect on the ignition switch or the instrument panel.
To add a similar ground jumper from the potmetal gauge housing to the column support isn't a bad idea. With a dedicated ground attached you can power up the panel before it is screwed to the dash.
Shimming a steering column is a new one for me. If the bearings in it are good it should locate itself. The steering column isn't centered up properly with the radius cut in the inst panel. Never has, never will. Only Chryslers engineers know why.
To try and get a perfect fit there will cause scraping noises in the column and shorten bearing life.