I installed a new intake and headers and completed the EGR/air delete. The car won't even maintain idle it runs so rough. I did something wrong somewhere. When looking things over I found the piece in the photos below not connected to anything. Can someone help me out with what it's supposed to be connect to? Is it part of the EGR system that I should have capped off?

 

Don't think i have that valve on my car. It's for sure a vacuum line of sorts, being by the HVAC. Everything that you took off, if there were open lines left that went to the manifold or TB, make sure you Cap them off. I am willing to bet that you forgot to cap something off, and that for sure will cause crappy Idle.

 

Did you make sure to reinstall the small vacuum line that connects to the back passenger side of the intake manifold?

 

I'm pretty sure that's not part of the egr. The left Side looks like the hvac vacuum lines. I have Always seen a T fitting there...

I agree, it sounds like something that should be capped isn't capped. Ran great before mods installed? Any codes?