Chainsaw Repair

In a situation like this I would first increase the idle speed screw. Then I would try to adjust the low speed mixture screw for best idle. And then try to lower the idle speed. You need to make an evaluation of the high speed mixture also. There may actually be more problems?

There are three possibilities here:

First and most important is that you may have a vacuum leak in your engine that is causing an overall lean fuel mixture running problem that is more pronounced at low speed. This is often the seals on the crankshaft bearings but can be in the connection between the cylinder and the carburetor. This will require a pressure vacuum test of you engine by a competent chainsaw mechanic.

You have a impulse line from the engine to the carb that is kinked or broken.

The low speed part of your carb is plugged with trash or corrosion.