Over at Tonkota's place last week, we were trying to figure out what this brass looking thing on the back of the 3FE intake manifold is. There's normally a plastic gray cap that snaps on over the top of it. On his, the screw in the middle was missing completely, and on mine, it had come completely out (but was kept from being lost by the gray cap). I reinstalled the screw (which has a little black O-ring on it) and snugged it down, and it seems to have increased not only my mileage, but I noticed a decent seat-of-the-pants improvement in power. Felt like there was a noticeable increase in low end torque. My question is, WTF is it?