I just purchased a 1979 Starcraft Super Sport with a 1979 Mercury 85 horsepower 850. It idles fine but when I try to accelerate it, it coughs and sputters. The guy I bought it from said he took it out and it accelerated fine but when returning to pier it coughed and sputtered. He had to get back on the idle because it would not accelerate. He told me that he just rebuilt the carburetors. I drained the gas even though he told me he mixed it 50:1. I also checked the spark and it has spark on all four cylinders. Everything seems to function fine. I have ordered carb rebuild kits to rebuild the carbs just in case a needle valve is not in the carb correctly or loosened up. ANY HELP would be appreciated.
