I recently bought a brand new one myself, and I had the same issue.
Get about 12 tanks through it or so and it should clear up. Don't push it real hard though (it shouldn't be pushed hard anyways, it's a 30cc saw, it doesn't really have a lot of balls).
The sprocket tip of the bar was really tight on mine. Take off your chain and make sure that sprocket is spinning freely. If it isn't, just lube it the best you can just cut little stuff with it - don't cut anything bigger than 6", I'd suggest just nipping away at limbs for quite a few tanks....
What kind of gas / oil you using?? Use 93 octane mixed 50:1 with NON synthetic oil for at least the first 10 tanks. Mine was running real smokey and stalling at idle as well. The dealer said that the Stihl synthetic was lubing the motor too good and the rings weren't getting hot enough to seat - resulting in some fuel to slip by and burn up in the muffler.
Check your spark plug and make sure it's clean and run that thing at high rpms for a few tanks in small wood.
That and also be sure not to lean into this saw. As I had stated, these saws rip, but don't have much torque. A 200lb guy burying the bar of a 170 in seasoned locust isn't the smartest of ideas.
If all that fails take it to your dealer and ax wat da dilly iz.