it shouldnt have anything to do with the intake manifold or throttle body because all d series parts are interchangeable. it might be a sensor on the intake manifold somewhere. Check all that and also the throttle position sensor on the back of the manifold might be a problem. My buddy had an idling problem in his hatch and it was the throttle position sensor and the little screw under the circle on the front of the throttle body that adjusts the idle. hope that helps a lil. good luck