well my friend you are not alone with your dolmar 117, have the same model plus having same problem. Has good spark good compression on my gage about 110 psi enough to make me want to throw it after pulls my wrist apart. Saw runs good for five minutes then quits will hesitate first then take off then stall. Have done all you dit including mistry oil(good stuff). Talked to a Teck some place yesterday he didn!t have much to offer but said Try directfuel into carb after it stalls, I tried this after about four hand wrenching pulls she took off for a few seconds then died. I now suspect fuel distribution problems. The tech did say to check and change fuel filter and Tank vent system.If vent is obstructed it may put tavk into a vacumn and fuel pump cannot draft fuel any longer.When I opened tank fuel fill I heard a sucking sound around the seal on cap. You need to check out vent line amidship under carborator for dirt or foreign debree .There is a section on how to clean this in your operating manual
lol Bruster