i have an older Harley gas golf cart. from time to time it decides to just sputter and spew out blue smoke. when it does this it take a very long time for it to start running again. You have to push the gas pedal just slightly and keep it there as it is sputtering and trying to start. Once in a great while it has back fired when shutting off. could this be a bad gas problem or something more serious. . i have put in a air filter , gas filter ,new spark plug and plug wire last year.