95 avenger es undercharging...

I'm having problems with undercharging and repetitive RPM surging. I've changed the alternator/ regulator, belts, cleaned and tightened connections. I had the computor changed last year and all this stopped for a while but it recently started doing it again. Obviously something electronic is causing the undercharging, surging, and causing the computor to go out, but I can't figure out what it is.