He means the EBPV, (Exhaust Back Pressure Valve.) If it closes, you'll hear a nice hissing sound, and a noticeable loss in power. I'm thinking your MAP sensor is going back and its cutting back fuel, prolly from going whack. Try to get a "P" number for the code and we can help you more. Most likely going to an electrical/sensor issue though.the oil is the Crank Case Vent it is just below the intake tube comes up from the drivers valve cover.
That sound like a foot in the exhaust sounds like the EBBV closing which would cause the boost sensor issue.Boost sensor codes would be related to the map or the EBBV.You could always wire the thing open or pull the plug from the bottom center of the pedestal and see what happens.