Air flow sensor if it runs fine if you use very gentle throttle but stalls or falls flat with heavy throttle. May have to swap a known good one in to verify, alas, as it won't show up on diagnostics as a bad MAS -- usually a communication buss error.

Crappy diagnostics, if you ask me, but then computer stuff these days is uniformly terrible.

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!