2000 Ford Mustang While Driving Headlights Lights Through Out Dash Will Dim

While driving, my headlights and the lights through out the dash will dim and brighten. Then, when coming to a stop the car will start to idle, then the gauges will all drop and about 5-10 seconds after, the car will die completely. Also, sometimes when tapping the break or toggling the button the moves the driver seat forward and backward the inside light flickers. Any ideas