Leftover hose after replacing valve cover gaskets

[Howfer]

I just replaced the valve cover gaskets on my 2003 4.0 Explorer. When I was done, I had an extra hose of some kind - vacuum I think since it had no hose clamps. It tried starting it anyway and it started but runs real rough and won't idle. Can anyone identify this hose, tell me if it's possibly causing my problem, and where it belongs? Thank you!

 

[drdoom]

Maybe PCV or IAC valve? And that's definitely the cause of the problem.

 

[Howfer]

Maybe PCV or IAC valve? And that's definitely the cause of the problem.

Thank you! That led me to search for PCV valve replacement and I saw where the hose is supposed to go. It's running much better now!