Has the top end of this motor ever been opened up with new valves and springs with 404 hrs on it,it might be time to start thinking about it.

That is on the agenda for this winter, but I have to solve this problem as I don't think the top end is creating the issues I'm having now. It would be a shame to do all that work and have it be a fuel issue...but thank you, I know these motors are infamous for top end around this amount of hours.