This hands loosely under the hood. It almost looks like those old floats in the back of toilets.

 

Looks like some sort of misplaced rubber bump stop that's come lose from somewhere ???

 

It's the vacuum reservoir for your AC/Heat controls. It should be mounted on the passengers side inner fender.

 

Yeah it's got a small line running to a little outlet just beside the furthest spark plug on the engine.

 

Yes, vacuum reservoir, should have TWO vacuum lines

 

OH, no its definitely just got the one. Is it very important?

 

Yes, very important, it allows Vents in the cab to direct air flow to Panel, Floor or Defrost, Defrost vent is default, no vacuum in cab = default

It can also be hooked to EGR system so EGR's vacuum controlled valve can be used during acceleration

It can use just one vacuum hose if it is "T"ed with a check valve
There should be a vacuum diagram in the engine bay, look for VAC RES and its hook up

 

Most things in the engine compartment tend to be important lol.

 

All those functions still work as it is, I haven't noticed anything odd with the vehicle other then the placement of the reservoir so I'm wondering if maybe it's just the way its supposed to be hooked up, yet placed in a different area.

 

UPDATE : Pretty sure when my mechanic was doing the safety (replacing ball joints) he removed the reservoir by accident and neglected to put it back in it's proper place.