I'm thinking of going through my whole engine bay before I put the
new intake on. I'm looking for vaccum leaks, are there any that wouldn't show up with the throttle body spray. Any clues or leads I can take guys?

Also, the ISC, if it's sticking or working too slowly, is there anything I can do to it while I have it off, besides the normal clean, should I lube the spring inside?

Can the valve on the brake booster be taken out and put back in, I have a new clamp on the hose, but it's hard to get that plastic valve out?

Vacuum gauge is an inexpensive tool yet very valuable for engine diagnosis... particularly for checking for the existence of vac leaks.

Spray brake clean, carby clean, or aerostart around any suspect hoses or gaskets. The idle will change if there is a leak.