So I just got a freshly built 421 banshee. It starts up and high idles but once you put it in gear the idle goes back down to normal. Then when you go to get on it, it sounds like it’s sputtering and when you get all the way to 6th, it sounds like it’s turning off and on. New spark plugs. I synchronized the carbs today and i got the idle issue fixed but it’s still running horrible.