I've got a vibration that feels like a bad ujoint or wheel balance, but I am pretty sure that is it engine related. It is not always there, just shows up around 1500-2200 rpm (usually around 40mph in 4th gear). If I put in the clutch and coast, keeping the engine rpm at 2000 the vibration stays. If I have the clutch in while coasting and let the rpms drop, the vibration drops or goes away. If I rev it over 2200 or so, the vibration decreases or goes away.

The injectors are fairly new (maybe 15000 miles) the ip mileage is unknown, but probably replaced in the last 40K miles (as stated by the prev. owner). I've run diesel kleen in the fuel tanks, with no change. Timing is within 1 degree of 8.5, the truck starts usually in a couple of seconds even when cold (20F) and generally runs great.

The only 2 other problems I have is a random clunk that I think may be coming from the dm flywheel while idling and occasionally the starter gear stays engaged when after the truck starts. I usually shut it off and restart it and its fine. Maybe the clunk is the starter gear not retracting and hitting the ring gear, but I think it was there with the old starter and after I had the dmf put in.

The truck has 193K miles on it, with fresh ujionts tire balancing and alignment.Any ideas?