Electrical load problem

Follow the output wire from the alternator to the fire wall pass thru. I'd bet a beer that you have a poor connection, Either at the firewall. or somewhere between the alt and firewall. Look close at the outside of the plastic on the firewall connector, there usually melted slighty cause mopar used too small a wire guage. I would just run a nice 10 guage wire to some point inside car, if memory serves it runs to the amp guage.
Also check for Bad Grounds. that's a common culprit too. Just cause you cant see it dosent mean maybe your negative batt cable is bad.

It a cheap fix i'll tell ya that.