On my car its the hose from my cold air intake to the drivers side valve cover. its leaking something all over the valve cover. What is the hose for? This past week if im driving at a steady rmp, the car will jump or stutter a little.

 

The hose that goes from your intake to the valve coverconnectsto thePCV valve located right in the valve cover. It is vent for gases thatwant to escape from the engine so everytime you step on the gas, vacuum from the intake sucks all the fumesout of the engine. It is a must have part, if it's leaking from around the PCV then itis bad or the gasket around it is cracked. It will hurt your performance and gas milage they are not expensive and are sold at any part store