I have a 371xp chainsaw that spits, sputters, and sometimes backfires. I'm stumped because I've done everything possible to solve the problem. I've taken the carb completely apart and cleaned it, the spark is nice and blue, the compression is perfect, the rings and cylinder walls are fine, the arrestor screen is clear. Basically it will sit and idle on its own, but when I pull the throttle it backfires, sputters and sounds like it's going to blow up in my hands. Anyone with advice or knows what it could be will be greatly appreciated. Thanks, Scott.