I had the same thing happen.It would act like a plug was fouling and you would change the pplug and it would be fine sometimes from 2 mins to 30 mins and then act up again.Sometimes i would get mad and not change the plug and 20 mins later the cylinder would kick back in.So I took the coil off the pto cylinder the one thatw as acting up and swapped it with the center cylinder then the center cylinder was doing it so i figured out the problem.