I have an R reg Xantia 1.8 i 16v when engine gets up to temp it starts revin really high when idling. Drops off when you go to drive off does any one know what this could be ? I've been told an air flow meter or my choke is stickin and various other things ....... Citroen themselves where no help at all.
Try the ICV (Idle Control Valve). These can be cleaned with carb cleaner. If that doesn't fix it, i'm afraid you've got to by a new one. They are usually quite easy to change but do refer to a haynes if required.