check the battery and the terminals and lead wire to the battery.......
it might not be getting enought juice.... one of te cells in the batt might have gone bad... giving it enough to start but not run properly.. that happned to me once..... the car ran ok but the bass and + terminla were shot... it started and drove but backfired and hesitaated if you got on it .......
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200 points away from a 300