mk3 mondeo - irratic idle when warm - rubberball

when i approach roundabouts or junctions and stop the tickover will fluctuate between 500 and 1500 rpm, and even cut out ,this only happens when the engine is warm, but is ok when cold. any ideas what can cause this.

mk3 mondeo - irratic idle when warm - Peter.N.

Petrol or diesel?

mk3 mondeo - irratic idle when warm - rubberball

1.8 petrol