Chasing down my high idle gremlins, I was exposed to the concept of the diagnostic utility of Duty Cycles (a.k.a. Lambda On/Off Ratio) by the following posts and website:

'Adjusted' lamda tower screw...car won't start.
'Adjusted' lamda tower screw...car won't start.
560SL diagnostic port/tool
560SL diagnostic port/tool
380 SL idle, oscillates between 500-750 rpms
380 SL idle, oscillates between 500-750 rpms
ODB 1 code reader
ODB 1 code reader
Bosch KE3-Jetronic Mixture Adjustment
http://www.landiss.com/mixture.htm

Unfortunately, my current arsenal of automotive tools does not include an oscilloscope or a Duty Cycle capable multimeter (although I ordered one last night from Sears).

In the meantime, I was determined to try to decipher the method of getting the car to tell me what was wrong with it.