Rotax 912 running rough all of a sudden?

Engine has been running great. Flew last weekend and then Wednesday was going to fly. Started up and it was sounding rough at idle. I warmed up a minute and advanced the throttle and it continued rough until it got to 3000 rpm. Let it warm up some more then ran it at 3000 rpm for a couple minutes hoping to clear up the problem. No joy. I ran it at high idle and turned off the fuel valve. After a while it smoothed out just before it was starved for fuel. Opened the fuel valve before it died and it ran smoothly for a few seconds before it began to run rough again. Sounds like a carb problem where maybe one carb is getting too much fuel. Mag check at 3k is normal. I dropped the float bowels and the floats looked to be floating normally. Fuel looked clean. I had run on this tank for a couple hours Saturday. Gascolator had clean fuel. Suggestions? Why would a good,running engine start running rough after just a few days?

Are the starter carb cables and return springs allowing the arms to fully return to the off position?
Any debris in the carb bowls or in the float needle valves?

Some things that came to mind.

Pull off the bowls and weigh the floats. Sounds like a float went heavy...

Check your intake manifolds as well, could be torn.