its really quite difficult to pinpoint what that could be, it could just be the cold, or it could be a subtle (in your case, noticeable) exhaust leak. if it were engine mounts, the everything would shake like a ***** and you'd know it. does it shake real bad? and i'm not talking on a cold start because i'm sure every one of our diesels on here will do some jarring and jittering on a cold start

good luck

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