I've searched, just couldn't find the answer I was looking for. My car seems to have a problem with running as it should. Half the time it'll run smooth, idle fine, etc. as it should. When it's running great I don't hear a thing out of the n80 valve from inside the car and today I noticed when I don't hear it and I go to fill up the gas cap actually has pressure behind it when I take it off.

When it's running bad; idle dips a few hundred Rpms, exhaust sounds bad, doesn't run as smooth as it feels like if should, gas cap doesn't make a sound when I get some gas, and it just feels like it has no power to it. During this you can hear the n80 valve clicking like a ***** inside the car and you can smell gas outside of the car sometimes. And the click is LOUD.

I know it's supposed to click from time to time but my car runs bad more than good and when it's running bad the n80 valve makes itself known, clicking all the time. Could it be malfunctioning and messing with my fuel pressure/trims?