Engine over revving??

[BurntCarcus]

Hi guys, posting this on behave of a m8 who has a 1.6 Mégane Coupé-Cabriolet. Basicaly when he is changing gear and puts his foot on the clutch the engine revs up about a 1000revs extra before dropping away. I think it also does it at lights and stuff as he get strange looks from everyone thinking he is a boy racer lol Any ideas as why the engine dosent drop down revs as soon as he takes his foot off the throttle?

[jamieator]

i had a similar problem before with a different car and it was a sticking throttle body which was causing funny fuelling and causing over revving at lights and stuff