mondeo 18 cc m reg?

This sounds like the Crankcase Breather Valve is getting blocked, When this is the case, the engine will stall when warm but not when cold. Its located in the PCV housing above the exhaust manifold on the front of the engine block
To remove it for cleaning, remove the exhaust heat guard and the rubber T piece under the coil. Reach under the Thermostat housing and you will find a small bolt holding the metal pipe on. Remove this. Now reach your hand in under the pulse air piping and give the rubber tube a good pull (Pliers help) and the valve should pull out. Clean it thoroughly with WD40 or the like and replace.

Steve J
August 2007