Yes they do. You will find it located under the MAP sensor on the opposite side of the manifold from the TB. Be very careful when removing the MAP sensor. The clip that holds it on break very easily! Unplug the sensor, GENTLY squeeze the clips and pull up. Then you can twist off the cover and get to the PVC. The Haynes manual for 1985-2000 GM full size FWD (#19020) shows this is some good detail. I seriously recommend that anyone working on our cars get this book. It has helped me through some serious shyte.