Can someone tell me what the hose behind the intake is for?

I will do my best to describe it. This particular hose runs from one valve cover to the next, on the passenger side it just slips over the little pipe. On the driver side it looks to connect to a much bigger area. The back rubber hose has a sensor plugin connected to it. The reason I ask is because mine is completely broken, it is just a black hose hanging on the back with the sensor connected (not to the actual hose but just for reinforcement I assume). The driverside is ripped off, giving a total of three hanging pieces.

 

Its part of the pcv system. It runs from the rear of the driver side rocker cover and goes to the rear of the pass side rocker cover and then to the front of the pass side rocker cover. The sensor on the back of the intake your probly feeling is the map sensor in the intake itself. Get the tubes replaced.

 

Thank you, would this explain my oil leak as well ?

 

Is it #4 here?: www.ls2.com/boggs/controls/engine.jpg Part of the PCV system, #4 is listed as "crankcase vent" for a '98.

 

Yes that is the one, does it need immediate replacement and would it cause my oil leak?

 

I would replace as soon as you can, and yes thats why you have oil leaking.