In my case the pcv was working properly when I had oil pooling in the intake manifold. This is why GM designed a valve cover. 2007 is when DoD (Displacement on Deman, later changed to something else) came out on the Tahoe. Mine has it. Oil consumption should not be occurring, even if you have DoD. I still think you should check and clean the throttle body before we get any further into this. Also, running Lucas Oil Stabilizer won't hurt, but I doubt it'll help too. Another thing I thought of today was, have you tried done a seafoam treatment recently? If not, I recommend it. It'll help clear up the top end of the engine.