i had that code, it ended up being a vacuum hose that ran from the little valve thats above the airbox to a valve on the backside of the intake manifold (of couse, this was on a 2.0). If the vacuum hoses are fune, and the air pump runs when you first turn on the car, it will probably be that valve above the airbox. But 90% of the time, it will be a vacuum hose.