I have a used OS FS-26 4 stroke engine that starts easily but won't keep running after I move the throttle back to idle. I start with the mixture screw turned out 3 1/2 turns. I turn in the mixture to get the RPMs up, lean it up a little then move the throttle back to idle. When I open it up quickly, it responds slowly the stumbles then stops. I richen the mixture a bit and it starts right back up. I turned the tiny screw, air bleed I think, with no effect.
What is the basic setting for this adjustment? What am I doing wrong?