90 Grand Caravan alternator problem?

I have a 90 GC with the 3.3, I have a problem where after an acceleration and letting of the gas, the voltage meter drops and becomes eradic before returning back to the normal voltage, this causes my lights to dim at night and has me worried that one day it won't go back up, I have replaced the serpentine belt so I don't think that is the issue. Does anyone have any ideas? could it be the alternator or is the belt slipping?

Is your battery old? I had the same problem with my 90 Caravan. I had a voltage leak (a light in a storage compartment was never going off) and it was draining my battery on a cold winter night. As soon as I found the leak, I never had that problem again. I recommend you replace your battery.

The battery holds a charge just fine and powered everything just fine with the engine off aswell. , and no lights stay on, as far as I can tell lol. I'm not sure how old the battery is, it came with the van and iv had it for over a year.

Well, if you're not sure about the battery, then I would say that's your problem. Just because it holds a charge doesn't mean it's not weak. Sounds like your charging system is working overtime to charge it, which is not good for your charging system. I usually replace the battery when I'm not sure about it, just to be sure because modern cars require a lot more juice than they used to.