this happens on my rs1800 fiesta and it sounds like above , head gasket not clamped down properly or head slightly warped causing dampness in the bore causing it to miss fire when started from cold. do you have alot of water vapour coming from the back of the car when started from cold? . mine does the exact same in the morning then drive for ten seconds and its fine. just to note as its only using a very small amount of coolant theres no cream under the filler cap.
i know this on mine as the water pump impellor broke when we had all the cold weather and i drove it for 50 odd miles with very little coolant in.


cheers paul