On my 52 plate 172 i've got a really annoying problem. When i pull up to a junction and depress the clutch the revs just drop until the car stalls. Its fine when driving and there are no warning lights coming on. Seems to be happening more and more. Sometimes it doesnt completely stall but just seems to hold onto enough revs to JUST about idle (200-300rpm instead of normalish 800rpm). Very annoying when this happens every junction! Any ideas/solutions pls?