The alternator is currently at Powermaster and they have been testing it and they can not make it fail.

Review:
The test machine at NAPA told the technician to reverse the field wires to be able to complete the test.
My ammeter fluctuates at idle and up to about 1500rpms, then it smooths out after 1500rpms. It did not do this until my last drive of the season. My system voltage jumps back and fourth from 13-15 volts while the ammeter is fluctuating. A new voltage regulator showed the same results.

I am trying to give them all of my info so they can keep checking it but I am not sure what else to tell them before they try and send it back to me. Is there another type of voltage regulator that I can test? My current two are the NAPA brand. I do have a Chrysler BLUE (constant output) regulator that I could test if needed.

Any suggestions are appreciated.