In the bottom pic you can see the rubber line that sticks into the under side of the intake and runs to the PCV valve the goes into the breather box on the back of the engine.
It isn't actually a valve per se, it's actually an orifice tube that is always open. It allows a small amount of air to pass into the intake at all times.
The four runners were all gunked up with black crud. After soaking the whole intake in parts cleaner for a few days, then going through it with a pipe brush, it is immaculate. The gunk is from blow by gasses that are drawn in through the intake hose that connects to the valve cover.
There was also a lot of crud built up where the injectors stick into the intake.
After reinstalling it, my idle was a high (1800 RPM). After checking and rechecking everything for possible vacuum leaks and not finding any, I adjusted the idle at the idle screw on the front side of the throttle body. I also had to make a small adjustment to the screw that acts as a stop for the throttle (the part the throttle cable wraps around).
It's running perfect now, and a bit smoother than it did before the cleaning. Throttle response also feels better, the engine seems more willing to rev up.
If you intend to do this to your car plan on getting: intake manifold gasket, EGR gasket, throttle body gasket, injector o-ring kit x4, IAC gasket, and probably the PCV hose that goes under the intake. There are also multiple coolant hoses running to the throttle body and IAC motor. Also, with the intake off it is way easier to get at the four coolant hoses on the back of the engine if they need replacement.