Idle mixture must be set with a duty cycle meter or the diagnostics tool, duty cycle works fine (pin #3 of the diagnostics connector, the round one with a screw on cap). Lots of posts on this, and it may cure most of the problem. Just twiddling with the screw usually makes the problem worse. You can get close with a CO meter, but it's much more difficult. Set duty cycle to near 50% at idle, hot, value must float.

Timing is mapped and computed, so if it's off, it's due to a bad temp sensor (I don't know the values, but they can be checked with an ohmmeter) or bad crank position sensor. Worst case is a bad engine ECU or ignition box, both rather expensive and I wouldn't replace one without knowing it's bad.

A leaking injector will give you fits with idle mixture, too -- rough idle, stagger on takeoff (because the dripping one is causing the computer to set the rest too lean), but will run fine at higher rpm.

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!