Car is overcharging. Please help!!

I had some overcharge issues myself which caused my battery to boil over...I ended up buying a new alternator because the Diode was bad about a year ago (this was a BRAND NEW alternator). So, I took it back and they said it was a defect. But you also may replace your regulator. I recently had another overcharge issue with my duster and was thinking OH GOSH ANOTHER alternator....but I decided to change the regulator first, which didn't help. Then I got to looking and the plug that connects to the regulator which is the female end I think it was?, Was coming apar, which is a connection issue. So you may check that. Fixing that plug solved the WHOLE issue. I was charging at 18 volts when driving around 2200RPM and 16 volts at idle

Hopefully this may help?