From what I understand, that (vacuum) port on intake runner #4 is connected to 16Vs with automatic transmissions. For our manual models, it should be plugged. Mine's plugged with a 3/4" long piece of hose with a machine screw in the end. Maybe I also ought to check to see if it's holding vacuum. What's the procedure again? While running, spray some carb cleaner near the plug and listen for ???