Ford Fiesta 1.3 Duratec 52 plate,rough idle?

Any help would be appreciated,my Ford Fiesta 1.3 Duratec has a problem idling,the revs go up to 2000 dropping back to 1000 and so on,are there problems with throttle bodies on these or idle control valves?has anyone out there had the same fault,thank you for your help in advance.