Engine lopes at idle, drops volts when defrost on
Tonight coming home from work, I noticed the voltage needle started bouncing up and down while stopped. I got home and played with it for a little bit. When I turn on the defroster, the voltage needle drops to just about nothing. Turn it off and it goes back to center. I have just replaced the alternator about 200 miles ago. Any ideas where I can start. It has 208,000 miles. I have no clue when the plugs were changed, if ever.