Annoying Power issues!!

sounds like something going to ground. if amp gauge going out, the car would die. if main fusible link was going out, the car would die. it seems to me that you have a loose connection under the dash. check the main welded splice under the dash, where the main feed from the bulkhead connector comes in. it splices off to your ignition switch, fuse box, amp gauge, and headlight switch. the headlight wire should be the thickest black wire going to the switch. check for power at this splice WHILE the problem is going on, then follow each wire until you find the problem. this is where a test light will be your best tool.