I have an 03 6.3. When it goes into high gear, 50 mph or so something starts shuttering. It feels like the old f150 Ford shutter on steroids. It feels kinda like a motor mount is broken but I know that’s not it. It also seems to have lost a lot of power. 192,000 miles and it’s been doing it for awhile now. I’m only using it to drive to work now bout 20 miles a day. Any ideas as to where I need to start looking? Thanks!