Hi I need help ASAP!

[Hammau23]

I just did new intake manifold gaskets on my 2000 Denali and I heard a vacuum leak and found it is on this hole. There is also a red plug that I don't know what it goes to and I need help with both of those things I will posts pic of the plug it is just a 2 prong plug

Please help ASAP!

 

[Goodinblack]

Post pictures