I have had the car for about 8 months, replaced the alternator about four months ago. About five days ago car started surging and bucking while driving down the road at about 50 mph. I turned off the ac and fan and the problem went away. It continued to do this off and on whenever I would turn the ac on or just the fan (set on PANEL for outside air). When the headlights are on and I try to roll up or roll down the power windows, the lights dim for a second. When I got into the car this morning and started it, the dash panel lights (ABS, Brakes, etc.) came on and the speedometer stayed at zero - car ran ok and did not surge or buck, but lights would not go out and speedometer stayed at 0. Started car up a little while ago and it ran ok.
Any help would very much appreciated.