This is an update/question I posted concerning a BR550 in the thread titled "Stihl BR550?" I just bought a BR550 and used it for the first time Saturday. I put gas in it and it started great and ran for an hour or so before cutting out. I figured it was low on gas so I filled it from the same tank. It would start fine and idle fine in the middle choke position but as soon as I throttled it, it would die immediately. Gamba and Martin suggested I just take it to the dealer so I did. They said it was old gas (they said they tested it). The gas was only about 2 weeks old and my MS250 chainsaw runs just fine with it. Are the new 4-Mix engines just that finicky? I usually fill my car when I fill my gas cans and my car takes 93 octane so that is what my lawn equipement usually gets. I used Husqavarna oil in the gas and it has a stabilizer in it. Should I switch to the Stihl oil? Extra stabilizer? I just don't understand how it can idle so strong and die when I pull the throttle.