You basically have an air leak from the impulse hose. It's a common problem on the 029/290 saws. Very easy to change. Your dealer will have it, it's pretty cheap.I have the same chainsaw and that happened to me this past winter. Someone told me there is a small rubber hose that runs from the crankcase to the carb that acts as a vacumn to suck fuel into the carb and it can crack. I haven't checked it yet since I have another saw.