My car keeps stalling.. there are a couple of factors that i think it could be. when i am driving my appliances seem dull like the stereo light and my dash light, and even my head lights seem to dull every so often. when i stall i can not get the vehicle to turn over it makes like a click click click noise, i thought it could be battery, but when i check it its around 12v. next i thought it could be the starter so, i tried banging it lightly with a stick and it started up but then it idled at 3000 rpm. my mechanic said it needed an serpentine belt but i think the starter has a part in the problem, thanks