jazzmandolin

86 22re. When I start the motor all seems good without touching the throttle and idles fine. The alternator light comes on and does not go off until I give it some throttle? Once I engage the alternator it wants to run a little rough and sometimes the idle rises and falls just a little but does not die? Seems like it has bit of a miss once the alternator kicks in. New plugs wires, ox sensor, mass air meter. Coolant seems to be where it should be every time I have checked it. Any clues?