what does this plug goto

I think this is a air intake TEMP plug but not sure. also don't know were it goes. it has the same type plug that is on my water TEMP sensor. also note the small breather hole on the oil fill cap..could this cause be to run lean ? I see that the privies owner has a filter be hind the cap to keep dirt out

shoot no PVC

Jason ..thanks ! but the motor I just put in (yes its the old motor) it is a fresh rebuilt by my local NAPA/Ford guy.
so I should not have a oil control issue.(blow by etc)
now that you mention PVC valve I don't remember putting on back in when I put the intake on? I took all the extra plugs on the bottom side of the upper intake and plugged them and I have one pipe coming out to the back that the vacuum tree hooks to and the fuel pressure reg.
SO do I need to go and look to put the pvc in ? I mean this oil cap that I have now plugged to..just below it on the oil fill tube there is a hose that runs to the intake of the throttle body. so I don't think the inside of the motor will see pressure , it does have some were to go, but I am not sure now that i think about PVC stuff...
hang on ..........i remeber now it is on the back side of the lower intake ! woo i was worried there for a min..forgot were i ran it too, but i do remember now its there.