Outdoor Power Equipment and Small Engines - stihl 047 farm boss starts, but no power

I borrowed a couple of Stihl chain saws from my Dad - the 009 and the larger 047 farm boss. The 009 is somewhat newer and runs fine. The 047 will start but only runs in choke or with the accelerator pushed for short times out of choke before it nearly stalls. It never runs full throttle to cut the big tree (trunk is left) that fell in my back yard. I replaced the spark plug already. It hasn't been used in a while. Should I work on the carb and how?

Thanks in advance.

if they sat for a long time with unstabilized fuel in them, really......long time with stabilizer... the carb does need some work, as for how, order parts if you need em using the serial numbers on the saw. carbs easy. also check the little intake screen on it, is a mesh screen, can get clogged.