If you tune it for when it's warm (as you should) it'll be lean when it's cold. That's ok as long as you let it warm up before you run it hard. Some guys will rev the snot out of the saw as soon as it starts.
I had an intermittent problem that I couldn’t figure out either. Saw ran fine but would lose power or even sometimes die while cutting. It ended up being the fuel supply line in the tank had a hole in it and when the gas was low it would start sucking air. Dealer figured it out and replaced the line. Works great