So i notice slight oil residue on and around the valve cover and notice that i'm hearing the turbo more as well as the dv, (stock except chipped) and have been trying to look for a potential problem. Also, it seems that i only boost around 18psi spike then it drops off towards 15, 12 or lower. In 5th or 6th however it will spike around 17 or so and hold that with a slow taper as rpms increas which sounds normal to me.
Anyway, after searching i saw that the way to check the pcv valve (i guess the check valve in the pcv) by removing the tube that connects the pcv to the intake manifold and blowing in it... The pcv valve is fine by this method.
Another thread discussed trying to remove the oil cap while the engine is running. My oil cap is sucked tight and if i pull up on it at all to break the seal the car starts to stumble like it will shut off if i remove it. This is a breather issue? Where is that located and what is it breathing? Why does cause the engine to wantto shut off if you remove the oil cap?

Also, how do you check your dv? you can just remove the 3 screws and pull it out and check the rubber?