Exactly what part are you referring to as the air mass meter? The fuel distributor?

Have you checked the fuel pressure and the differential pressure in the fuel distributor? They can go bad from corrosion in the diaphram between the upper and lower halves, causes the engine to run way rich.

Did you re-set the fuel mixture?

More details, please!

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!