if the alternator light is flashing that means the system isn't charging. chances are the brushes in the alternator are worn and they are floating at rpm which causes the no charge condition.
you need to pull the alternator and check the brushes as that can be replaced on its own, otherwise its a new alternator
but confirm that the battey is good and holds a charge
and it is known that these cars do weird things when there isn't enough voltage coming from the battery
