I have been troubleshooting the P0401 code and have already replaced the erg solenoid and cleaned the valve and cleaned the vacuum tubing. There was one particular piece of tubing that I had a question about. There are two tubes right near to each other, one has a green stripe on it and the other has a white stripe. The one with the white seems to have a bulge about an inch away from one end, and it is hard. I can't spray carb cleaner through, it just doubles back. I don't know if it is supposed to be there, or if this is something I should replace? Any ideas?