very rough idle

Kevin,

Thanks for the input on the grounding of the ignition modules.  There is an early service bulletin (SB-912-006) on the possibility of poor crimping on the module ground lead ring connector but it doesn't say anything about multiple independent ground wires.  Any other thoughts on where I might find more info on that?

Sam,

Looking again I found the service bulletin that defines the float max weight at 7 grams (for both floats combined).  

Since that sat so long I agree there may be debris. Pull the carbs. You can do it now or after days of things not going right then pull the carbs.

I weighed the floats and they were all below the spec max.  Per a previous suggestion, today I adjusted the float levels in each bowl to lower the fuel level in an attempt to achieve a half full bowl at idle.  After a small adjustment the engine started and idled better but as I lowered the idle down from 2000 to 1800 fuel still dribbled out of the left carb vent tube.  After another adjustment to lower the level further the engine is starting and running well again.  It now appears that the fuel levels in both bowls was set way too high and as a result the float needles were not able to close enough to stop venting fuel overboard.  The engine is now running as smooth as it ever has and I haven't even accomplished the pneumatic sync yet. Adjusting the float levels appears to have solved all my starting and rough idle issues.  I suppose there is a point where the fuel level in the bowls can be set too low and that may lead to some other unforeseen issue but the issues I've been struggling with are now all gone and I'm happy again.  Thanks to all who contributed to helping me resolve this issue.

The proper measurement is the carbs are held upside down, measure from the lip of the carb to the top of the brass float armature. It should be 10.5 mm.if it were 10 or 11 mm it wouldn't be causing this issue. Don't just set these where you think they are okay. Use a MM ruler or the Rotax tool to verify the proper measurement.