One-wire alternator help

I have a Powermaster 140A alternator on my '90 306 and it started acting up yesterday. I don't know if it was the cold, or what. I started the car and the volt gauge read battery voltage. (it's done this before, it's normal cuz of my idle speed and the turn-on speed of the alternator) i then revved the engine to get it to start charging, and it pegs the volt gauge! i verified with a DVOM and it was slowly but surely creeping up past 18 volts. what is going on with this... i checked all the 4 gauge wires and theyre tight...

marine_2003: the stock voltage regulator is on the back of the stock alternator, so that's not causing a problem here.

i know its got an internal regulator. it HAS done this once before...i THINK i fixed it by tightening a connection somewhere, but i cant remember. there arent any loose wires right now that i can find.

btw, this alternator is based on the GM Delco 10SI series alternator. do you think if i got a "one wire conversion kit" for gm alternators that that would come with the parts i needed? or should i just call powermaster?