Locate the valve, apply the rust penetrant to the valve retaining bolt, and allow the bolt to loosen for a few minutes before removing it with socket. Detach the vacuum lines and electrical harness from the valve, and pluck the valve from the engine.
Place the valve on a rag, use carb cleaner to spray the valve, and wipe off the dirt remnants. Take caution to prevent the cleaner from entering the electrical components.
If the rod does not slide smoothly, soak a cotton swab with the cleaner, and rub the port and rod to remove the dirt. Finally, reinstall the clean valve into the engine compartment.