ok its deff the tube that goes from your intake to you valve cover if you dotn have one get a section of hose that will go from it to the intake it will be maybe a foot and a half at the most if and it should connect to the intake on the throttle body side of the mas air flow. its more then likely on the bottem of the tube.
its part of the venting system it brings filterd air inside the crank case the the only bad thing is it bringing in anything like dust, water, bugs and its allowing it to be in side your crank case. wich will lead to oil passages stopping up and other parts to be destroyed.
Yes, it's the PCV Closure Tube between the large fresh air tube and the PS valve cover. Without it, the engine is sucking dirty air directly to the throttle body/IAC and also through the engine internals to the PCV valve and then to the intake manifold. The air/fuel ratio is affected because unmetered air is entering the engine through both leaks.
IIRC, the original parts were a plastic tube and a rubber elbow. Fix it ASAP.
At idle and light throttle, the oxygen sensors may be able to correct for the lean condition, so you may not see that much fuel economy difference after it's fixed. The most important thing is getting the engine sealed up against the dirty air that is getting in now.