Jumpy volt gauge

I have the same problem with my car and I have changed out the regulator a couple of times I think it stays good for a while than it starts the bouncing back and forth. This last weekend I took apart the bulk head connectors and cleaned them ran a seperate ground wire from the regulator to the battery and also checked voltage at the back of the alternator with a digital meter and it show's it bouncing. Also checked wires that run through the ignition switch and found that the ignition switch was loose and tightend it but it still bounces. I had a few issues before with the wires not being on the right post's with the blue and green wire at the alternator; would this ruin a regulator? I have have done all the upgrades that MadElectical suggested, it still charges just bounces back and forth like others have stated before it drives you crazy. I'm sure i have the wires run right now between the blue and green wire on the alternator so I will go ahead and change the regulator again to see if it will stop the bouncing. I have also tried a new alternator and it does the same thing. do you guys know of anything else to try?
Pat Faley
67 Notchback
East Peoria IL