Our friends across the pond have been dealing with this issue. Apparently it was worse on pre-2003 duratecs:
Whether or not the later 'tecs are immune is unknown. A decided clicking noise from the manifold is the tell-tale.
2001 Amazon Green ZTS 134,000mis Died of rust after 15 years on the road
2012 Sterling Grey SE Sedan M/T!
2016 Kona Blue SE Sedan M/T!