Another symptom will be approaching a junction after say, a long stint on the motorway, and when you dip the clutch, the revs drop and it nearly stalls. When it's really bad, it might actually stall :)

thanks mate il keep an eye on it. its only a slight variation. not so worried now.
thank u

If it's a slight variation, don't worry about it.

But, if it's dipping really low i.e. 500RPM then going up to 1500RPM, then it'll be the idle valve.

The revs in my 1.6 did vary slightly.

right here goes i have nt long bought a corsa 1.6 16v sport on an s plate off a guy on here, its nt on the road yet due to insurance, i have heard that the idle control valve is a common fault on the sports, and i think mine is on its way out, if nt could sum1 suggest wot it could be:

when its running its fine no missing no problems wot so ever, but when its idle the needle on the rev counter moves very very slightly up and down and when i go to the front of the car the engine is nt idling smoothly its more up and down its nt oil or service problems as its been serviced about 100 miles ago :look: if its the idle control valve how much to buy and fit and if nt wot else could it be?