I just purchased a new stihl sh 56 ce blower/shredder vac this past weekend. I started off using it to blow all my leaves into a few piles, and then used it to vac everything up. Till all was said and done, I ran 2 tanks of premix through it. My issue is, during the first tank and a half, it would bog down, almost to the point of stalling if I mashed the throttle wide open, and ran rough at part throttle. I had to either ease into it, or blip it a few times to wind it up, then I could go full throttle. I thought I bought a dud, but then thought, maybe I should give the engine to break in and loosen up. salesmaned up vacuuming leaves, then switched back to blower mode to blow my porch off. This is when I noticed that it was running better. This was close to the end of the second tank. The boggy throttle had all but disappeared, only bogs down for a split second if I mash it, and it was running much smoother at part throttle. It's not 100% yet, but much better, and does seem to have loosened up some. Do you guys think it's just a matter of breaking it in fully, or should I take it back to the dealer to have the carb adjusted? The first tank was gas that the dealer put in it when I bought it. They took it out in the shop and made sure it started OK while the salesman rang me up. Don't know how old the gas was they put in it, but it was still acting up after I filled it the second time with my stuff. I bought a six pack of the stihl ultra oil and mixed a bottle of it with a gallon of ethanol free 89 octane, which the manual calls for. Would have preferred 93, but the only station anywhere around me that sells pure gas only has it in 87 and 89 octane.