Hello Forum! Lately,my high high mileage '82 300 sd (355,000) has been intermittently running rough with the shakes. Motor mounts were just replaced and valves are adjusted properly. The scenario is from time to time, I will pull in to my driveway and the engine will start to shake strongly and act as if it is missing and behaves like it has a bad motor mount with lots of shaking. It does not do this everytime which makes me wonder what could cause intermittent rough engine running on a diesel. Could a failing lift pump cause this or other? Injectors are new and were properly calibrated by Bosch shop. Perhaps a clogged main fuel filter? Any thoughts out there? Thanks!