check the lambda sensor plug under the footwell onthe o/s the tend to fill with water so have poor contact on the pins.
otherwise check the throttle position sensor wiring it should have been modified by ford with a new connector and shrink wrap.
it all else fails try the ht leads and plugs as they can fowl the plugs quite easily.
if all else fails pm me there is a few other things it may be but not much point in going into this now!