You'd think ford would have learnt with these valves, i had a fiesta turbo , various XR2i and they all did this. Its an absolute pain when you pull up to traffic lights !!

I found cleaning them didn't work for long, I got a new one in the end.

My escort has sometimes started to think the idle valve doesn't exist in a morning with the car cold, i have to have my foot on the throttle for a few minutes.