Hello. I have a 1999 Subaru Legacy gt 5mt and when the car returns to idle at stop lights and what not there is a very noticeable dimming of all the lights on the car. No ligh turn on on the dash but after checking the voltage of the battery the altonator only puts out 13.0 volts at idle. Once’s the engine leaves idle the voltage returns to 14.0 volts. I have a new altonator so I’m wondering if this is normal or if the altonator is going out again. From what I’ve read it could also be a bad ground but I have no idea where to check for that. Some help would be greatly appreciated.