You don't want to idle a 2stroke for too long, but the blasters can idle for a while alright...just don't let it idle for extended periods. When you do have it idling, rev it up a tiny bit here and there.
Sounds like you must be running too rich. Running a little rich is good, it keeps your motor safe! If you've got it jetted for the cold and it's warming up, that could be the problem.
I always rev the motor up before I turn it off to burn off any extra gas/oil hanging around. It helps keep plugs from fouling.