When I start the engine it runs very roughly for about 5 seconds (something like only three cylinders would work). It is happening only when the engine is cold. The car has 75k km.

Any suggestions??

change sparkplugs? Or coilpack ****** up? No engine managment light lighting up?

It does sound like maybe an injector is leaking or something is fouling a sparkplug. Try changing the plugs and start the car from cold , if it doesnt have the fault with clean fresh plugs then you should investigate further , one of your plugs maybe dirty or damaged?