Lights flicker and gauge jumps around???

Darthomas said

I've changed some things, but even then I stick pretty much with factory parts.
I won't try to tell anyone what to do, but I've seen plenty of people who add problems seeking speed over reliability and dependability.

Click to expand...

The symptom you describe is very common with mechanical voltage regulators, even new ones, because setting the charge/discharge contacts, spring tension, and gap between the armature pole piece is really tough to get right, and when wrong that's exactly what they do.
I expected your Duster would have an electronic regulator, and I haven't encountered that with the electronic type.
Let's move forward and figure this out.