[W126 Coupe] Idle Air Motor???

[Alexander Hochhausl]

OK Gents I have a new mystery. Yesterday I got in the car and noticed it
idled a bit rough when it was cold. Once warm, better, but still a bit
rough, and have an intermittent (random) miss, like a sputter, every
5-10 seconds - when stopped in drive. I notice my vacuum is a little
lower than normal. After stopping in drive after driving, the vacuum is
low, then creeps slowly to almost normal in a few seconds. 

I checked for vacuum leaks, but found none - throttle closes fully. I
suspect maybe the idle air motor (valve) is being temperamental? Can
this be opened up and cleaned? Any other things I am overlooking? I
doubt it's ignition related as it is not a 'regular' miss. 

One other symptom I have always had is that on occasion, when starting
the car at neither cold nor 'normal' operating temperature - the idle
'lopes' between 500-800 RPM, every 3 seconds or so in neutral for a
minute or two, and then settles down to normal idle. But if I put it in
drive, it holds steady at 600 RPM.

.... oh do I miss the days of carburetors .....

Thanks All, 

Alexander Hochhausl, PE
Tel: 516-909-3794
'89 SEC 560