Yes, there were some of the early ones that blew plugs. There were enough of them (as well as other Ford engines), that the after market developed kits that install steel inserts for the aluminum head. These inserts can be installed without pulling the head. The kits cost about $400 and any competent Ford or private garage has them.
Ford made changes to eliminate that problem in about 2002. The newer (2006+) engines have lots of improvements including another 50 hp and and extra tranny gear. Don't fret about them.