If there is any vacuum line comeing out of the opening in the intake runner behind the carb. plug it off & see if that effects the engine. A vacuum leak in this area can act like a miss on 2 cyls. because it draws on the one runner. Get some plastic pliers & pull one plug wire at a time & see if you can isolate it to one cyl. It even helps to lock the emerg. brake good & put it in drive. This is a poor mans Sun machine. A rich carb can put soot on the plugs & cause missing & rough idle.
