I have a 99 vw beetle 2.0. I went on a trip drove 1200 miles in a week. But before I went I had valve cover gasket replaced. The mechanic broke the intake hose while taking it off so he replaced it with a rubber hose. Needless to say when on my way home my CEL came on. Well, took to Advanced auto store they checked it and said misfiring #4 cylinder. I had intake hose replaced spark plugs and wires even a oil change. The CEL still on and still reading same thing? I need help! What can it be? It's running rough!