We have seen at least a few instances of "tuneability" issues with MTronic saws. One thread in particular stands out on the 661. That was Funky Sawman's saw. Yesterday, my 661 started stumbling and hesitating coming off idle. Actually, it's in the hands of another member. I have never experienced issues like this with a 661. They have always had lightning throttle response in my experience. The first thing I thought of was the module on the carb. Isn't that the part people have been replacing real cheap, for something like $15? Then I went in Funky's thread and see where they replaced his ignition module and intake boot. Now I'm confused. Can anyone clear this up for me? Thanks in advance.