My 1992 Yamaha Golf Cart does not run well on start up. It sounds like its running on one cylinder out of two, but it only has one. After a minute or two, it smooths out and runs fine except at shutdown when it somtimes backfires. I've changed the plug and wire and adjusted the carb to no effect Can you Help? Gary

Optional Information:
1992 golf cart G9 A

Already Tried:
plug, adjust carb