Re: Float Stuck ???or Ice Building Up In The Carb Somehow???
Usually a carb ice problem results in a stuck slide - preventing the engine from returning to idle, that doesn't sound like the problem yer having. Also carb ice would only be an intermittent problem depending on ambient humidity - at -15 Celsius odds are the air would be really dry... so I don't think icing up is the problem, I'd check for a sticky float.
If you still suspect carb ice, the next time it happens pop the air filter off and peer inside - it'll be ringed with frost & ice and really easy to see.