yes, they do go bad, but usually that means leaking at idle and dribbling.

Have you had the fuel pressure tested correctly? If you have a bad pressure regulator, they will often flood out, ditto for a bad diaphragm in the fuel distributor.

Is the idle mixture set to give you nearly 0 mA at the EHA at idle?

Cold start valves have been known to leak, as well, but that won't give you good idle and flooding on acceleration.

Have you verified that the idle switch is indeed working and that the oxygen sensor is good and functioning? Have you replaced the over-voltage protection relay?

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!