I posted a few weeks ago about a 1600 that didn't run right and my buddy and his dad tried almost everything, well almost. A couple guys on here said to check and see if there was a hole between the exhaust manifold and the the intake. Today all day three of us had time to take a look at it and pull it apart. Once the exhaust and intake were separated we couldn't see any problem. We then put the intake manifold in a vise the way it would sit on the engine. We then poured some gas down between where the intake and exhaust bolt together ( don't worry we were safe, no open flames ect please dont get upset). It poured out the carb flange as fast as you could pour it in. Manifold must have a real big hole or crack letting the engine suck exhaust while running. They are going to order a new manifold and problem is hopefully solved. This has been an ongoing problem and to be honest when they told me how it was running I never thought of a manifold leak between the two ! Thanks for everyone's replies and responses ! His dad is real happy his tractor will run right again. Probably be his best Christmas present ! Thanks again guys !