the idle speed is controlled by the idle speed controll valve.
funily enough.
this is the most common problem on all efi fords.
take the iscv off and clean it right out with petrol.
use wd40 etc and make sure its all clean and lubricated.
this usually cures it.
if not then ckeck for air leaks on all pipes around the inlet manifold area.
it seems to be more common on cvh engines and i believe its because they are engines that seem to produce loads of oily mess, they always clog up around the inlet manifold area for some reason