i’ve been having some lean codes and took off the ufo on the valve cover and shook it and heard no rattle, are they supposed to rattle? I cleaned it with a lot of cleaner and it seemed clogged but the cleaner became clear on the other side but took a while to come through. i also tried to suck/blow air with my mouth and it was like it was stuck and nothing was going or coming through. Think it’s a bad valve?

 

The ufo ones do not rattle. They have a diaphram that reacts to intake suction for full flow at high rpms. You should be able to easily blow or suck air thru it. If stuck closed it will allow excess pressure to build up in the crankcase and possibly create oil leaks. Replace asap to prevent this. Sometimes they even hiss when you really listen. That is ok. Their design is to allow max flow while preventing oil from passing thru into the intake path and preventing a backfire thru the throttle body igniting the gases. Most pass a little oil i have read on here. If you replace it, check the connections on the hose ends for sealing tight and no stiff o rings

 

If your hose looks like this, here is the one i bought