Replace a clogged 1979-1993 Mustang PCV valve with direct replacement parts from Latemodel Restoration. Your positive crankcase ventilation valve (PCV valve) reroutes blow-by from the crankcase to the intake manifold and back to the engine where it is re-burned in the cylinder as part of the air/fuel mixture. When this gets clogged, it causes driveability problems. Add a new hose, filter screen, and grommet to your order for added assurance. Get the right replacement for your 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, and 1993 Fox Body Mustang at 5.0 Resto.