Im surprised nobody is suggestiong oil intake by the intake manifold through breather lines..My E320 has two breather lines which could let oil in if passages were blocked and it also has a valve cover breather attached to the intake air..the loss of a baffle above the ports would cause oil to flow into the intake in high volumes..looking into the crankcase ventilation system.. burning oil tends to blue, trans fluid is grey and stinky! (I had your leaking vacuum modulator valve, I know!) And water will show white smoke.. And Im not sure if anyone mentioned a valve guide??