Originally Posted by RadioFlyer

BOV sticking? Also, check your PCV/breathers. I've found that that changes the idle a lot. You don't need to change them, just pull them off and shake them. If they rattle, they're fine, if not, they may be gunked up and you can just shoot brake cleaner through them until they rattle. They are a one-way check valve, so make sure you're shooting the brake cleaner through in the right direction.