318 ammeter erratic?

This seems to be a cyclic thing as opposed to just simply erratic?

Actually the two symptoms / causes could be related.........a bad connection

It could also be the regulator itself

Look underneath your regulator. If there are two great big wirewound resistors, this is an old "contact type" electromechanical relay. I would replace it.

Make absoLUTEly certain the regulator is well grounded. Scrape the mounting, and the VR flanges clean, and use star lock washers. Make sure the bolts are tight and not stripped.

Also make sure the voltage drop to the VR IGN terminal is not excessive, and that you have good, adequate grounds between battery, body, and engine