I have successfully avoided buying any more car parts this week, so didn't check in to see if the pickup fixed the problem. Will do so soon, what with all the cars I have something will need fixed soon....

Intermittant problems can drive you nuts -- it's usually fairly easy to find out why something doesn't work at all, but when it works sometimes and sometimes not, you have to actually catch it in the act with the correct equipment attached, and that gets to be quite a game.

A bad coil that gets hot can have it's internal resistance skyrocket, delivering poor spark, although I don't know if it will be late or not (the one I've been talking about has a new one). I suppose a dislocation of the crank position sensor or flags (or magnets?) could do this, but unless something is loose and flopping around, it's not likely to be intermittant!

The only other thing to check is wiring and connectors -- corroded or broken wires will cause all sorts of problems by being sometimes conductive and sometimes high resistance. Usually not a problem on a Benz, at least before 1994, but always possible. A big hassle, but may solve the problem (Hans has an S500 in at the moment that has a bad connection for the heater in the O2 sensor -- works fine once warm, but will set a check engine light periodically because the O2 sensor isn't hot at idle).

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!