I assume you are talking about the "microswtich" on the linkage as opposed to the throttle position switch (TPS) on the end of the throttle valve shaft.

The mircoswitch is easy to test and if it misbehaves you might even be able to clean it. In my case the problem was the TPS and both the TPS and microswitch must operate properly to activate the idle stabilization system to control idle speed.

Duke