Quick ICV question '86 560SL 117 engine
 

If I unplug the ICV electrical connector, engine idling, and no change in the idle speed occurs, whether the engine is cold or warmed up, does this confirm that the ICV is bad and should be replaced (or cleaned)?

Engine idle was previously doing quite a bit of 'hunting' (speed up & down) at cold idle. I found 1 vacuum line disconnected, 1 large rip in the rubber gasket under the air intake (repaired with silicone sealant for now).

Tell us first what is the RPM while the car is idling.

Cold start, idles at 1,000, then drops after a minute or so to about 750. I pulled the connector while engine still relatively cold, and the idle surged up to 1,000 again. Plugged it back in and it drops to 750. Still minor hunting/surging. However, unplugging the ICV when the engine is warmed up seems to have no effect. Normal?

not normal,speed should go to 1500 or so.sounds like your icv is very dirty or jammed.

If that happened to my car I'd clean the ICV with a carburetor cleaner spray such as AC Delco.