What is this part?

Yep, should be sealed by oring if memory serves.

 

So I’m pretty sure that nipple I shared a picture of had an o ring or something that belonged between it and the intake. I just fashioned a pretty tight o-ring out of some spare vacuum hose I had laying around and now that big vacuum noise is gone!

idle is way more steady, no weirdness after I blip the throttle, feels like it’s actually supposed to now!