Sounds kind of like an impulse line, but that usually causes them to stall on any throttle activity. Also look at the muffler screen for being clogged up. That will casue the same problem as a clogged air filter. Seems odd though... I have had many saws in the 290 line and never had that kind of problem. I had similar problems with a 250 and a 210. The 250 had a vacuum leak and the 210 had a cracked impulse line. Neither held a tune until they were fixed. Usually when a fuel line goes they fail to start or start and stall out right away. The impulse line is a hose that runs from the base of the engine to the carb where it drives the fuel pump. Make sure that the carb is seated tightly with the 2 nuts that hold it in place. If the carb gets loose the impulse will fail and/or air will get into the intake. Make sure there are no cracks in the fuel line, the impulse line (looks similar) and that the fuel filter is OK and that the gas line is not kinked. It seems like a starved fuel situation to me. Flywheel/coil timing is hard to move with the way they are mounted. The coil may be failing, but that is rare on a newer saw and it would likely fail all around and more at peak RPMs.