[Pyrotechnic]

Yes the breather and it's filter are necessary. That's a factory item and it has a purpose, even though it may look a little rough on your particular truck. There is a small filter over the opening in the air cleaner housing that keeps oil from blowing all over your air filter and if it's gone, that could be the problem. I believe you can actually buy replacement filters if it's missing or too gunked up.

If you decide to switch to an open element air cleaner, make sure you replace that tube with a push in style breather.