Lights flicker and gauge jumps around???

I am fighting the same thing. Converted to 2 field alternator, electronic regulator and ran a 10 gauge wire to the alternator from the starter relay (battery is in the trunk). I removed the wire from one side of the factory amp gauge and put it on the other terminal effectively using it as a tie point. My voltage is over 15 volts at the alternator. I measured the ground potential difference at the regulator at 0.165 volts. I am suspecting that I may have a leaky or shorted diode in my nice chrome Voltmaster alternator. I will try swapping my factory alternator in when I get back home on Thursday, I will let you know what I find, it might help you.