Car Stuttering at 3500 rpm??

[Majikal]

I was driving along this morning, looked at my volts gauge and saw that it had dipped down near 12, so I rev it a few times and I hear the belt catching and it goes back up to near 14volts. A few minutes later, it dips again, and it continues to go back and forth a few more times down the road. I pulled over and turned the car off for a few minutes thinking I should give it a rest. I turn it back on, pull away, it dips to 12, and now whenever the tach hits 3500, it stutters like it's hitting the rev limiter. This happens in all the gears. Any idea what this could be?

[jlevie]

A system voltage of 12v is close to the point that the DME will cease to operate. If the battery is fully charged the system shouldn't see lower than 12.6-12.7v, even with a dead alternator. Of course, with a dead alternator the batteries voltage will drop pretty quickly and can cause what you are experiencing.

The bouncing system voltage could well be worn out brushes in the alternator. Or it could be a bad power or ground connection.