Ford focus 2002 1.6 zetec has had new timing belt fitted but now it idling a bit rough it has died a few times when stopping at lights etc and the idle is dropping below 800rpm and feels like it going to die it doesn't matter if it in neutral or in gear with clutch down it still the same also when parked and rev up to anywhere between 2 and 3000rpm the rev counter will drop and so does the power please help the idle control valv e seems ok along with everything else i had new clutch put in but not the release bearing would this cause the problem? please please hgelp me thanks

also i forgot to say that it didn't do before the timing belt was fitted and when you say the transmission i take it you'd be refering to the clutch release bearing(clutch release slave)also the revs are fine except from the 2000 and 3000rpms range and it has a little pick up when at that rev mark i was gonna change the fuel filter as it the original one from new so thats done 110 thousand miles any additional info would be much welcomed thanks also i forgot to say that it didn't do before the timing belt was fitted and when you say the transmission i take it you'd be refering to the clutch release bearing(clutch release slave)also the revs are fine except from the 2000 and 3000rpms range and it has a little pick up when at that rev mark i was gonna change the fuel filter as it the original one from new so thats done 110 thousand miles any additional info would be much welcomed thanks