Just got my car back. Despite spending a ton of money I am still trying to sort it out to make it a proper fd. Long story. Anyways I am playing around in the engine bay and tightening bolts underneath etc. enjoying the hobby etc.

I notice this nipple on the side of the manifold. Should it be capped?
Please tell me this is the solution to all my problems. Fat chance.

 

Closer

 

That nipple does not see direct vacuum. It is merely a pass through to the other side of the intake manifold.

 

Sounds like I can leave it alone

 

All those are pass throughs. I'm guessing mazda put them there so they didn't have to rought rouses around the intake manifold. You don't have to do anything with them. Sometimes I cut them off for a cleaner look. That particular one is EGR while looks like I welded up.