Ford Focus Cmax - Hanging throttle - mjr693

Hi Guys

I have a 04 1.8 petrol Cmax with a throttle problem.

When I rev the engine to approx. 3k and remove my foot from the pedal the revs drop to about 2k and hang there for about 1.5 to 2 seconds.

This only happens when the engine is warm.

Anybody out there got any idea what causes this?

Cheers

Mike