is the small blue wire harness thingy, running parrell with that mystery hose, is that your oxygen sensor that goes in your air intake? b/c...if it is then you know where that leads, so you can only guess the other one leads to the same place...and what goes into the throttle body...Air and Fuel right?...so...and obviously if there is a leak somewhere you'll lose gas mileage...so This is my being a dumbass and just re-evaulating my stupid guess, lol. Hope it helped.