I bought and installed a 130amp alt from grand re builders last year along with the big 3 wire upgrade. The truck runs fine but when I'm at idle and increase the rpms just above 1000 the head lights and the lights inside the truck get brighter. When I idle back down to about 800 the lights dim. Anyone know whats going on? Can I just adjust my idle to a little above 1000 avoid any issues in the future?

Thanks.