ORIGINAL: jcmccorm
Sounds like your idle mixture is hosed. I'm not familiar with the TT engine so someone correct me if I'm wrong. Find the idle screw (usually opposite the carb from the main needle valve). I'd run it at the lowest throttle setting you can keep it running at and turn the idle mixture screw until it smooths out. Just like the needle valve, clockwise is lean, counter is rich. I wouldn't have a guess as to where you're at now so try one direction and go the other way if it gets worse.
Cary
I've messed with it and I can get it too smooth out but only at high RPMs. Low enough it would still be considered idle but high enough it moves the plane on grass. Once I lower the RPMs to the point where the plane doesnt move, thats where it gets rough.. It sputters a bit and finally dies..