Small Engines (Lawn Mowers, etc.): chainsaw, exhaust outlet, carburetor

Question
I HAVE A STIHL CHAINSAW MODEL 028 AV SERIAL#216211664 WITH 20 IN BAR. BOGS DOWN UNDER LOAD AND WILL NOT IDLE. CHANGED SPARK PLUG, AND AIR AND FUEL FILTER WITH NO LUCK UNSURE WHAT TO DO NEXT. CAN YOU HELP ME

Answer
ken
A big part of ensuring a smooth-running engine is keeping your carburetor and linkages clean and well adjusted. The linkages attached to the carburetor's throttle and choke plates can bind or stick when dirty. Constant vibration and wear can affect the setting of the carburetor's mixture screws (if equipped).

Sounds like it is time to rebuild the carburetor.Try cleaning the
exhaust outlet muffler screen, carbon build-up will cause problems with idling and bogging down.