hi there
did you resolve your problem yet? is the car turbo or non-turbo? If turbo, check turbo air supply from air filter to turbo. The main supply of air from air mass meter to turbo. Check that all clamps are tight and that there are no leaks in supply hose. If there are, you must change this hose. If your power is hesitating as you accelerate, then check all air supply hoses to intake manifold along with all vaccums. Good luck