[jthraen]

It definitely sounds like your alternator.

I was driving my GTV6 in rush hour traffic on the 110 at the 101/5 interchange. Twice I stepped on the brakes and the radio turned off. Then the car started sputtering and coughing. Somehow I crossed four lanes of traffic to get to the shoulder before it completely died. Turned out that my alternator was producing just enough power to keep the car running. The radio was just too much.

A beautiful CHP officer pushed my car off the freeway to safety. She and I....well that's another story.