Hy Panelit, did you clean the intake manifold on the inside from one end to the other? There could be something in there stopping the air/fuel mixture getting to the front two cylinders. Other than something like that, I would suspect a vacuum leak at the front of the manifold, put a vacuum gauge on it and see what you get. You can also check for vacuum leaks by spraying carb cleaner at the junction of the head and intake manifold, or you can use a propane torch [not lit] in the same way, be careful, please keep us informed.
