my taurus charging system light first started being on and then all my dials would go down and sometimes the radio would go off then everything would come back on. So I got a new alternator but the light still came back on. took it to auto zone and they said the battery and alternator and starter were all good.Got another alternator put in. Then the check charging system light and battery light started coming on. Got new battery and things are still the same. Sometimes the car will start and sometimes it will have a dead battery. Any idea whats wrong.