vibration

[lifesblood]

I have an 02 307 xsi,the problem is the whole car shakes when engine is started from cold and gets better as the engine warms up then drives fine.I've had a new coil pack and sparks but it still persists.I want to get it sorted before winter as its a nightmare to start and i can't just start the car to warm up and leave it for 5 mins as it will stall plus when i first start it i have to use the accelerator pedal to stop the car vibrating.Anyone have any ideas,its been to a garage and my friend is a mechanic and we can't figure it out,other than that its a lovely car to drive.