I had the very same issue. I had replaced the alt gauge with a volts gauge and that needle twitched at idle. I thought... Diagnose it or just buy a voltage regulator? Since I had pulled this alt', reg', electronic ignition, and more off a 73 Valiant a couple weeks earlier... A new voltage regulator couldn't be a bad move. Cured it.
I had the same thought. I had a new VR laying around so I installed it to see what happened. It did help seem to help some with bringing the voltage back to more normal levels, but the dang flickering issue seems to be just the same.
