This 2004 Honda Crv 2.4 Vtec had a p0507 code and no vacuum leaks.
Ive seen many honda IAC (idle air control) valves get corroded and stuck, causing a idle surge when in park or neutral, where the engine will rev up and down on its own.
If you suspect a IAC Valve issue, this video will show you how to remove it and clean it out/or replace if need be.
Your AICV might not be bad, it might just be stuck... Hope this video helps! Thanks for watching FixItPhillip! Please be sure to Subscribe!

CODE P0507 : Idle Air Control System Higher Than Expected

This Procedure applies for 20022004 honda crv 2.4L, but may also be helpful info for other Hondas/Vehicles