Hey guys- looking for some opinions. I just bought my 94 model IV, when I got it seemed to run rough, I chalked most of that up to sitting( I think it has been sitting most of its life imo) fixed a few squawks, changed plugs, rebuilt carbs with new gaskets and needles, checked float level, synced. The problem is this- at idle to 2500 the engine shakes violently and the gearbox is making lots of noise. It shakes so much the right carb pukes a little fuel from the vent line. From 2500 up it smoothes out, pulls cleanly all the way to 5250. I have triple checked the jets, sync is right on from 1400 and up. I think there is something wrong with the gearbox- seems weird it would be bad at 145 hours Any Rotax techs close to Spokane/CDA? Any input would be appreciated.

Thanks,

Scott