The 2 little plastic clips that hold these cables (one is throttle the other is ?) in place...

Noticed mine are in pretty bad shape and would like to replace.
See below.

Bushing for idle control cable: MB part number 1163020150

Front cable is from the cruise control actuator.
Aft cable is the cold idle control cable.

The black knob to the right of the headlamp switch on the dash is the cold idle adjusting knob.
Usually these are usually broken as a result of incorrect operation.

You need to introduce slack on the idle cable by depressing the accelerator pedal before you turn the knob to increase base idle speed up to 200rpm.
The coarse potmetal gear of the cold idle control cable (just behing the wood dash trim) is quite weak and will fail.

Typically you might need to adjust the idle when the car is warming up in the winter or to couneteract the drop in engine idle when the A/C is on.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Thank you for that. Actually sounds like this isn't too big of a deal for now.

My idle control cable actually is inoperable. Not sure if the linkage is broken or what but adjusting from the dash has no effect.
Another thing on the list, along with cruise amp, which is also inoperable.