I noticed the other day that my voltage fluctuating. Being that I have the stock guages I decided to verify their acuracy & wired my digital multi meter to a lighter adapter & noticed that it was indeed dropping from 13.9 down to around 12.5 volts. The odd thing was that it seemed to only do this under acceleration or when I hit a bump? I have a 135 amp alterstart alt & a new battery. Both are about 3 mos old. Does anyone have any experience with this? Thanks... Oh yeah, this is on the 1990.