On a 1998 Pontiac Transport with the 3400 engine, the PCV valve is typically located on the
valve cover. It's a small, usually plastic, valve with a hose attached to it. Look closely at the valve cover; the PCV valve is often near the back, sometimes tucked away a bit and might require some maneuvering to see clearly.
You'll likely need to remove the air cleaner housing and possibly some other components to access it fully for inspection or replacement. A repair manual specific to your year and model will give you the most accurate location and visual aids.
