I've been having the same thing happen in Georgia. It started pretty subtle Saturday night then Sunday it got really bad on the highway, to the point when I hit the brakes my car almost shut down. I asked a friend of mine, who is a mechanic, and he said it sounded like the alternator. I went and had my battery and alternator tested; battery tested good and alternator tested bad. I'm replacing the alternator right now, so we'll see how that works.