Long story short I had a temp gauge that was flickering badly for a while now. I finally noticed a lack of a ground strap between the engine and chassis. Once I added that things all went back to normal.

Check your straps if you've got electrical gremlins!

 

I would like to add to this. If ground straps are not hooked
up and with a good connection, if you have floor shift, the
engine will find a ground through the shift cable. Cables are
not cheap.....

 

The current will find the easiest path to ground. I was cranking the engine in a parts car and didn't realize the engine's ground strap wasn't well grounded. The metal line for the oil pressure gauge turned into the ground and was really heating up!

 

You can never have enough grounds!
battery to block, battery to body, block to frame, block to body, frame to body... as big as you can get! Braids work well, too.
I know some of that won't fly with the restonerds, but remember: DC electrons actually flow negative to positive.