I also have a 94 but its 2wd and have been haveing some slight electric issue too. I have a brand new battery put it alt seems good think I had it tested, mine is when I use my blinker my volt gauge will move with the blinks of the lights, I also here thumps through my subs if I hit brakes my subs will thump, if I have my headlights on its more prevalent. So it may be a ground not making good contact. I plan on redoing my grounds, I told you should have one from engine to body, body to frame. And it should be good ground straps or heavy gauge wire, the the shorter the ground the better too I have read.