Kaw420V 14HP single cyl. aprox 8yrs old. John Deere LX172 Last year it was a valve job now it is hard to start, backfiring, and it will "pop" when the deck is engaged. It also sputters like I am running it with the choke on (sometimes). From this explanation my dealer thinks its the ignition modual. Not the ignitor (that was new last year). The plug looks OK, not too hot and not too rich. Does this sound right? Yes the choke seems to be workin properly. When it runs right it runs great but it comes and goes when I stop it or idle it for a few moments. Any suggestions?