Yes, bad motor mounts will definitely give you rough idle. This applies to gasoline cars, too. The quick and dirty test is to asses the vibration standing in drive, then reverse. If the vibration is significantly less or gone in reverse, the mounts are shot.

Replace all three -- both sides and the rear tranny mount, too. The rear one is usually going when the fronts are dead.

If you haven't for a while, treat the car to a nice high speed high load trip of at least a couple hours -- does wonders for diesels. Put a bottle of diesel treatment in and go.

Your milage is about right -- I'd expect better, but 30 isn't bad in town. You should get 36 or so on the highway at reasonable speeds. If not, check for fuel leaks or dragging rear brakes. My Volvo TD (2.4 L turbo) gets about 29 mpg in town/mixed and 31-32 on the highway.

I'm looking for a 190D 2.2 with a five speed -- I'm going to have to provide my own transportation as a contactor soon, and need a car that gets excellent milage!

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!