Small Engines (Lawn Mowers, etc.): stihl chain saw, fuel air mixture, stihl ms 280

Question
I have a stihl ms 280 saw. When I start it and run it till it gets hot it sometimes won't idle down. Or it will idle high for a few seconds and then come down and sometimes stall. I have had the carb off twice and cleaned all the jets and checked the diaphram and everything looks good. Their is no blockage in the exaust and the air filter is clean. I also check the air gap between the flywheel and coil and set it at .10 and replaced the plug and it still seems to have the same problem. The jets are suppose to be turned out a quarter turn for the low speed and three quarters for high speed but the saw won't idle or start good if I leave them at these settings. When I make it richer it will idle and run decent but will still idle high and sometimes die out. I also adjust the idle screw to no prevail. I should do a compression test when it is cold and then hot and see what the difference is. Please let me know if you have any good ideas of what to try next. Thanks for your time

Answer
 Hello Jason:

 Set the Coil to .020in. .010 is too Hot. The Fuel Air Mixture Setting are for Starting Reference Only. The High Mixture is Set with the Throttle Held at Full Open and Then Listen to the Engine Revs. When they Peek, Reverse the Screw 1/4 Turn. The Low Air Mixture Screw is Set sa there is No Hesitation when Going from Idle to Full Open on the Throttle. Then Set the Idle. When you had the Exhaust Open, Did you Check for Carbon on the Top of the Piston? Hope this Helps. I am Here if you Require More Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John