My rancher 350 sat for a year, and when I started it up I went through the same thing. It wouldn't idle unless I kept the choke pulled out. I took the carb off and cleaned it, put it back together and it still wouldn't hold idle. So I turned the idle up until it would stay running, poured half a bottle of Seafoam in the tank, filled it up with fresh gas, and rode it for 8 hours this past Sunday, about halfway through the day it had cleaned itself out and I turned the idle back down to normal. Try Seafoam and just ride it a little it, maybe it'll clean itself out. Good luck.
*Edit: I didn't read all the way down, looks like you got the problem solved.