Nissan says never to clean it. Having said that, I have already done it, and it made no difference. It is in an odd place too. It is part of the throttle body and the sampling tube is an orifice in the side of the throttle body, with the opening parallel to the throttle opening and exiting into the main throttle chamber in a slot. I have also disassembled the two sides of the throttle body and cleaned both castings then replaced the gasket with a new one from the dealer. I also cleaned the IAC valve passages and the IAC valve. I have also cleaned out all of the EGR passages, exhaust gas tube, and the EGR valve as well as using the factory test procedure to verify the proper functioning of the valve and the components of the EGR system.
