90sr5_4runner

This probably belongs in the electrical section, but im going to post it here in hopes of getting a faster response. Anyway ive been having some problems out of my 90 4runner for the past week or so. At idle the truck runs pretty rough, the rpms hunt around 400-500. The headlights dim quiet a bit, and the volt gauge drops to the low line. this only happens when the truck is idling. I've also had to have the battery charged less than a week ago because the truck randomly wouldn't start because the battery was completely dead. I'm thinking it could be the alternator about to go out but i want some more input. I also have noticed that the coil wire shocks me every time i touch it. I changed the plug wires, but the coil wire that came with the new set wouldn't work with my truck, the plugs weren't the same. That may also be part of the problem?

Thanks for any help.