VW touran Sticky throttle

VW Touran 2004, 1.6FSI petrol.

When you lift your foot off the throttle, it does not return completely to idle immediately.

So for instance when changing gear, it sounds like you are dojng a bad gear change with the engine racing during the change.

In normal driving it slows down okay when you lift off the pedal.

I thought it might be just a sticky linkage, but on this car it looks like the pedal drives a potentiometer, so "drive by wire"

Is it possible the potentiometer is sticking, if so where / what to lubricate?

Or is this a symptom of some electronic gizmo or sensor playing up?

plug in diagnostic computer and check operation of clutch switch

I will do next time I'm over at my friendly garage.

So what does this "clutch switch" do then?

it tells the ecu when you have your foot on or off the clutch. if it doesn't know you are pressing the clutch down, it doesn't know you are changine gear so it won't drop the revs.

Doh, but you lift the throttle to drop the revs?

I'm not trying to do a fancy gear change without lifting off the throttle. So why don't the revs die away completely to idle immediately I lift the throttle regardless of the clutch.

I take the point about the clutch switch and will get it checked in due course, but I just don't see why it's necessary and why the revs don't drop immediately?