ok thanks guys for all the help once again. It will idle smooth and quite. Get on it runs great just like it should. cruising once again just fine. let off the fuel and knocks for a few seconds. Hopefully its not coming from the motor end. I was really thinking a fuel knock. No smoke either. If they don't inject any fuel at coasting then one must be leaking past dribbling fuel and causing the knock?
we do have a full bottle of that diesel clean and some 2 stroke oil in the tank now.