Perhaps he is thinking of what to do next. Oh, wait! that's me. :)
A chainsaw will stall for the same reasons as other combustion engines:
fouled plug flooded engine contaminated fuel bound...
it could be the tps sensor, map sensor, idle air control vavle, in jection problem, or something simple as a fuel fiter dirty, check the fuel pressure with a fuel pressure guage that you can pick up...
it could need new spark plugs orspark plug weir's
added by audiohelix:
many possible things could be wrong.
first and foremost see if it is throwing an SES code
if it is..the code will tell you...