I have a misfire on my 2006 Clio?

I have a 2006 Renault Clio 1.2 16 valve campus sport. I have only ownd this car a 3 mouth but in the last 3 week it has developed a miss fire. I have changed the coil pack , spark plugs , air filter and had the fuil filter out and it looks fine. Can any one help me with any sugestions on wt the problem could be. The car has only dun 46k.