Ford 2003 Mustang Workshop Manual page 1417

14. Disconnect the positive crankcase ventilation (PCV) valve and position it aside.
15. CAUTION: Do not use metal scrapers, wire brushes, power abrasive discs or other
abrasive means to clean the sealing surfaces. These tools cause scratches and gouges
which make leak paths. Use a plastic scraping tool to remove all traces of old sealant.
Remove the valve cover.
Remove and discard the gasket, clean and inspect the sealing surfaces.