Some things I have done so far. Please keep in mind I am having these same typ problems with my 100 and 106. I am pretty sure it is something I am doing...

Ign. is mounted on 1/4" grommets on firewall for ventilation. Diaphragm is vented into fuze, no snorkel, carb is openly exposed to air flow, Using Lawnboy ashless 50:1, Slimeline large dia in line filters...

I will try snorkels an see what happens. I just dont understand ho ground settings go to hell in the air and how a perfect running engine goes to hell in a few days. I'm going to pull the tanks also.