i never heard anything like it. i put a new one in it does the samething it rattles so loud you can hear it in the car. it only does it at idle car runs ruff at idle 87 305 tpi

The PCV valve uses vacuum to work. A rough idle causes a fluctuating vacuum signal.

Fix the rough idle and you'll fix the noisy PCV valve.

Could just be a bad valve. The quality on those things has gone downhill a lot over the years. I suspect they are all made in China at this point, regadless of whose name is on the box. If the rough idle started when you installed the new valve that could very well be it.

Also, some applications for whatever reason, like to rattle the valve at idle. My go-to valve for those situations is one for a 1991 3.1L V6 Camaro. I don't know why it works but it usually does when the recommended/stock replacement valves buzz at idle.

thanks... put in one from my 95 c1500 works great