54 plate Megane Scenic started cutting out, anyone any ideas?

Hi there,

I bought my Scenic in March 2009 and it's been running fine. Just recently, I took it for a drive to the shop and when I got back in it failed to start for about 5mins. It now routinely cuts out when I slow down to take corners although it idles ok at around 900rpm. Does anyone have any ideas what's wrong?