I have a 1999-2000 Dixon with the Kohler engine. It has had a mind of its own for years now. It runs perfect, then runs like crap. When it is missing it happens at idle as well as wide open. I changed the coil and spark plug a couple years back that didnt help. I have had the carb off several times, no trash in the bowl and it is never empty when checked and all vents, pickup tubes seem to be clear in the carb. The needle and float seem to be fine as well. I have had the fuel tank off and it had zero trash and the metal mesh filter was shockingly clean for so many years of use. Very rarily will the engine completely die, but it has done that in the past. The engine is clean, never needs oil added and its barely dirty at the end of the season. I asssumed it might be the fuel pump but it seems to hold good pressure as I have removed the line to make sure. Under a really good load in thick grass it will actually back fire sporadicaly while it is missing. It seems like a lean condition because there is no excessive black smoke from too much fuel. I have adjust the idle mixture all over the place and it doesnt solve the miss. Its aggravating because sometimes it will run flawlessly and then the next week it will have its miss as soon as I start it up. I guess my first move will be a new fuel line and clear filter to confirm fuel pressure, although I dont think its the issue having such good fuel delivery after checking it. Next the smart spark box or whatever they call the advance module which is pretty expensive. I just hate to have to take it somewhere and get 10 things replaced before they actually figure out what it is. I really like this little mower, but I am moving to a bigger yard and dont want to have put up with this any longer. Any of you Kohler gurus have any ideas? Thanks for your help!