CM 871 help please

[Ryeguy475]

Hello,
I own a 2009 871 450hp. It has a vibration under load that I just cannot seem to solve. When it’s parked I can rev it up and it’s fine, unloaded it isn’t too bad until...I go up a hill. Loaded it’s worse. I know it’s coming from the engine. This is what I’ve done so far... in frame 90k miles ago. New vibration dampener 4 months ago, new motor mounts, new clutch, reman trans. I did the injector leak test that I learned from Rawze, found #6 was leaking, replaced that. Made no difference!! I did the leak test again to make sure and it passed, no bubbles. This thing is driving me insane! I found a local Cummins “guru” that worked for Cummins for 16 years, he plugged into it and went for a ride with me, he agreed the vibration was coming from the engine. It’s almost like a slight fuel knock or similar. He did the cyl cutout test and it passed. The only thing he saw that he didn’t like was fuel pressure was 240 idle and 265 under full load when I was pulling a hill. He thought that was low pressure. My fuel economy hasn’t changed since this vibration started 6 months ago.[/align] Any ideas or thoughts are appreciated!