99 bonneville running on 9 volts (red zone)?

[MikeMichael]

Last week I started the car and quickly noticed the voltage was in the red zone at about 9 or 10. I already replaced the battery and positive battery cable and same problem. I've been told it's either the ground wires (which I cleaned and are all secure) or the alternator . The car still runs pretty good only now a little sluggish on take off and the blinkers don't work right. Any help greatly appreciated.