The idle control system on that pump is somewhat sensitive, and will cause idle problems if bad.

However, it WON"T cause running problems, it only controls the rack position for idle, I think. Unless it is full electronic control (unlikely -- I think the electronic controls are for boost and resonance flap position).

Having the injection timing off will cause problems, so will bad injectors or dead lifters.

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!