My tractor Harley is acting up...unsteady idle...after I bleed the fuel line...its ok for a couple of weeks...then starts up again...there's air getting in there somehow...can't see anything external...I have no idea..maybe a bad injector ? Fuel pump..? Haven't got anything to test diesel engines...I might have to call the expert...was planning to change out the fuel filter today.. but I'll wait until I'll talk to diesel guy...im gonna services the snowblower insted...