You know I was out jogging today & it crossed my mind that the unsteady ammeter needle would be from an electromechanical reg that ain't quite right or alt brushes/commutator (intermittent contact) but with your electronic reg that elims that. So I am thinking the alt if your idle speed is up high enough where it is supposed to be. On the high charging rate (which has to be dealt with) a sulphated battery would be the last potential but do continue to check voltage drops & jumping 12V to the reg "side" blue wire terminal would be my first step (a thin pin to stick in the triangle connector).