Help me diagnose high idle

[powerdbygarrett]

Help me diagnose high idle

Cant figure out my idle issue.

When I got the gtr, the issue already existed.

So:

Cold start idle: 1200

Warm idle: 1600

after driving for a while: 1800

While driving, between shifting, idle drops to 1000 than jumps back to 1800 in neutral.

I pretty much closed the IAC valve and had minimum effect. 

I want to try everything else before I open the intake manifold and check if the film is there there.

 

TIA!

[Steve85]

Disclaimer: I don't know much about Nissan engines, but... my old runabout ute, tends to blow off vacuum hoses. This leads to a high idle when stopped and on the brake pedal.

It also makes a sound you can hear, sometimes, I can be bothered to fix it, other times, not so much. Maybe a quick check of the vacuum lines is a good start? (like i said, i'm not an expert on this.) 

[Missileman]

Smoke test/ pressure test, clean the aac valve, and check the sealing compound around the butterflies has NOT been cleaned off.