I replaced the two PCV valves today. For some reason someone before me zip-tied the PCV valve assembly together. Maybe the hose was blowing off. Both valves seemed original, as they had "AC Spark Plug" stamped on them, not AC Delco.
I started the car up afterwards (I changed the fuel filter about two days ago too) and it idles very very smooth now. Just a hint of vibration to it, you can see it in the plug wires shaking barely, or if you put your hand on it, but it's much better. Plus, this was a cold idle with the AIR pump chuffing air into the exhaust.
The old PCV valves rattled, but a sort of gummy mushy rattle. If yours are old, you might consider changing them.
