I have used the tillison and the Walbro carbs for the past 9 years on my 3w engines. I find no difference in adjusting the engine for perfect performance. I find though that the tillison is a much better carb and actually will provide faster and smoother throttle responce. There is no problem with the heat coming off your mufflers going into your carb. There are thousands of 3w 100-106 engines out there running the same way yours is with no problems. I'm pointing fingers but usually when there is a problem its user error. You may have a case of a bad ignition so I would take the advice of the other guys here and see about getting a new one. Call up Bobby at Cactus Aviation and talk with him. You might still be under warrenty and end up getting a new one at no cost. But switching to a Walbro carb will not solve any problems.
Garrett Morrison