My new Stihl 180c doesn't want to stay running. Any ideas? Symptoms are a very smoking run...almost like there's too much oil in the fuel mix, but I was careful to only out one small bottle in 1 gallon of fresh fuel. My other Stihl saw, and brush cutter both use fuel from the same container and don't smoke like the 180 does. I checked the manual, and it looks like the only carb adjustment is for idle speed which I've played with and doesn't help. I can start it with the choke and can rev it to keep it running but as soon as I try to let it idle it dies within 5 to 10 seconds. The saw only has 2 to 3 hours of use...could a plug have gone bad? It is brown. I know I have a warranty, so I'll probably take it to the dealer but figured I'd ask here first to see if there's a simple fix I can do first. Just stinks to have to already bring it in.