It does not draw air from under the hood. It is a COLD AIR INTAKE. it and the original intake draws air from a hole in the radiator support. A hole that is behind the right headlight. I don't know if you have/had a restriction, or not, but I suggested that you look for an restriction in the old thread, http://www.gmtruckclub.com/forum/showthread.php/97520-Crazy-Idle-Issues#axzz26DAzginx you blew me off and opened a second thread. And, I see, with a little searching, that this is thread #3 http://www.gmtruckclub.com/forum/showthread.php/97165-Problems-at-Idle#axzz26DAzginx You changed the radiator and now it appears to be ok, you probably removed whatever was restricting the air flow when you changed the radiator. If someone else changed the radiator, you may never know what was causing the problem; but, at least, you could have taken a look to see if there was an restriction, instead of arguing with people trying to help you.