Major electrical problems

"Might be." You must be VERY careful and your huge mistake was in not removing the battery ground. The main power that feeds the entire car system except for the starter goes THROUGH the ammeter in the cluster. This means the black and red wires are ALWAYS hot, and the ONLY thing that protects them.....poorly....is the fuse link

Start by downloading a free factory manual from over at MyMopar. Some of the manuals there came from the guys here at FABO

MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

At the same site under the wiring section, is aftermarket diagrams, which are not always accurate, not always complete, but sometimes easier to follow.

Also while you are at it, please read this article:

Catalog

This gives a very good overview of the troubles "built into" this system and what to look for, even if you don't do these mods. AT LEAST make certain of the integrity of the bulkhead connector terminals, the ammeter connections, and read how and why problems can occur