I apoligize ahead of time for the lack of part names. I had a problem with oil (mostly vapors) running back out the tube from the rear of the valve cover and trashing my air filter. I took off the brass fitting at the front of the valve cover that has the tube that runs to the air intake and cleaned it out. It seemed to fix my problem, since it was just about completely clogged. That might be something to check that only takes a few mins, but be careful with the sometimes brittle tubes.