The "Microswitch" is in the throttle linkage nest and should be easy to see with the air cleaner off.

The "Throttle Position Switch" is located at the end off the throttle butterfly valve shaft - opposite end as the linkage attachment - and is more difficult to see on most models. (And may require removing the fuel meter if you have to replace it. Thank you Mercedes for the great "maintenance engineering"!)

The microswitch tells the KE controller to interrupt fuel flow when you lift completely off the throttle (and there is about a two-second delay built into the controller electronics) and resumes fuel flow when you step back on the throttle. By resuming fuel flow before the throttle valve actually begins to open, the typical "jerkiness" of single switch systems is eliminated making the transition back to fuel flow seamless. And the fuel flow interruption delay eliminates any jerkiness if you quickly transition between off and on throttle multiple times in quick succession - what the tech literature on the system refers to as "hysteresis". ("Engineered like no other car in the world", remember!)

The TPS sends an idle signal to both the KE-Jetronic contoller and the EZL ignition module to tell the KE controller to go into idle speed control mode and the EZL to fix timing at the programmed idle speed setting (see emission decal for that setting.)

The TPS can get dirty/sticky and not send the idle signal, which will cause uncontolled high idle speed. This is often overlooked as a cause of high idle speed. (It's not always the OVP relay!) Often just a good exterior cleaning of the switch and shaft will restore function.

DO NOT DIDDLE WITH THE THROTTLE STOP ADJUSTMENT!!!

The TPS has three leads - idle signal, WOT signal, and common ground. Proper operation can be checked by disconnecting the TPS pigtail at the engine harness connector and checking these circuits with an ohmmeter while you move the throttle to idle and WOT. Trace up the pigtail up to locate the connector. IIRC the center wire is ground and the other two can be quickly determined by testing for the idle and WOT continuity signals.

The microswitch is easy to check for mechanical and electrical function.

Duke