I have 2000 Accord 3.0L with P0401 insufficient EGR flow. I have clearing the intake plenum EGR port, the ports under the valve itself are as clean as I can get them as well as the port in the injector base. The EGR valve has been replaced, and when I test it off the car with jumpers, I verify it works. When it is install, and I jump it to operate the valve manually, the engine does not stumble or stall. Diag says if this happens to clean the EGR ports, and they are clear. When I blow air through the injector base port, or the EGR port, no air is passing between the injector base port and the EGR valve port below the valve. Is it possible the ports in the head are clogged? I cannot get 401 code to go away!! Help!!