oh yeah of course , sorry
Take to a local garage with diagnostic reader (try and find a local one other than a ford dealer who will charge the earth)
It should display the fault or give readings from the sensors and report back.The garage will then advise. With these sensors they can be intermittant, there are other sensors that could cause this but the one mentioned is the most common and fits your symptoms described. The only way to find out really is to have a diagnostic test rather than pay out to change the sensors by "trial and error" method.
stupid stuart
November 2008