A couple years ago my crankcase ventilation was creating a like oil blow-by problem were as the vent tube coming out of the drivers valve cover that connects to the air filter box at the filter was emitting oil over into the filter box. I change the pcv valve and thought that would solve it. It did'nt. Had a thread here asking what could be wrong. Reply was the motor most likely was having blow-by and probably needed to figure on replacing the rings.
I looked into it farther later on and what I found was the vac hose from the pcv valve to the ell fitting was plugged with carbon, and going further I found the metal tube/fitting was plugged as well as the "intake hole where the fitting threads into. I cleaned out the carbon from the lines and manifold and my oil "blow-by" problem ended, period.
I wished I had posted this back then for others may have had the same problem and did not find this.