well, I did have a problem with my 2166 stalling, but my issue is probably not very closely related, but do a search for 2166, or posts by me, and there's a particular thread that gives some very good suggestions.
My problem was that the machine had sat in storage for 2-3 years, and the carb was totally gummed up. the first time I had it in, they said the inlet needles were sticking, the second time I took it in, they decided they should pull the entire carb, and thoroughly cleaned it, which to date, seems to have fixed the problem. Hopefully you can find out what it is and get 'er fixed. good luck!