old farmer,u may have dirt in the fuel tank,that what it sounds like 2 me,try and get the tank off and swill it out b4 u do anymore,if it's missing like that i can't see anything else is at fualt,it shouldn't be the pistons or any engine problems,it's fuel it is im sure,if u have any more problems let me know ill all i can 2 help as im an mf dealerIJIJIJ