PCV Valve....lol. You know it's not working right if something is loose in it so you could even check the old one to see if it was even broken. We replaced ours but only because we had the CEL come on, but it's for a minor Evap leak that my friend ducktaped. He's eventually going to replace all the hoses instead of getting a smoke test. He used to be a mechanic. I don't think that PCV valve replacement is going to do anything...but I hope it deducts that reasons to get even more fixed.