Over reving megane

I have got a magane 1.6 RT. The car fraquently over revs its self at stand still usually in alot of traffic when I am not stepping on the accelerator at all.When I start moving again it stops. The engine also cuts off once in a while when im driving and I step on the clutch. Can anyone help?

i too have this problem with my megane. the garage tell me that they cant find any fault on the on board computer and basically have washed there hands of me.
did you get to the bottom of the problem if so i whould be very greatfull if you could share it with me.