Why does my Megane52 cut out unless I rev up the engine from a cold start?

My 52 Megane currently has an annoying problem, (whose Megane doesn't?). Each time I start the car from cold I have to rev the engine for about 10 secs other wise it cuts out. Its fine after this idling at about 800rpm. But when I stop the engine the problem reoccurs after about 5mins being stood. I know little about cars but i'm thinking could it be a sensor problem that's affecting air/fuel mix when firing up, sticky valves ?? any ideas would be great, Please avoid using the acroynym ECU ifpossible.

Cheers

Peter Hague
January 2010