Milage is about right.

Your electronic idle speed control is not working, idle should be 650-750 rpm and not change when you have the AC on or in gear with automatic (which I presume you don't have).

This is usually a broken wire at the three-wire connector at the back of the pump. They are at an bad angle and tend to fatigue. It could also be a major failure in the pump, in which case I'd leave it and live with it (you can set the mechanical idle up, but I don't know how!) until you need other IP work, it's very expensive on this pump.

You also very likely have collapsed engine mounts. Take a look at them and see how much space there is between the widest portion and the frame -- should be at least 25 mm, and you just be able to see the trapezoidal steel fitting on the bottom. If closer (they can actually touch) or if the steel portion has been pushed up into the mount, they have leaked out. The result is VERY rough idle and considerably more engine noise than you should have.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!