Engine starts fine usually when cold but shut off after a few minutes of running and try to restart you have to just keep cranking and cranking while using choke on and off engine makes spitting and popping noises and usually smell raw gas then all of a sudden engine will fire and run fine until you shut it down.Have replaced plugs coils and checked fuel pump and checked plugs for fire.cleaned and blew out carburator checked fuel shut off solenoid operation.Any help out there im at a loss with this engine.Has 450 hours