I have started to get a lumpy idle in my 94 740IL and of course the check engine light is on. It has 131k on the odometer. I was told by a mechanic that the pcv valve located in the rear of the intake plenumn, by the bulkhead, is the problem as its common with these cars. He added that I will see an increase in oil consumption and the rough idle is the result of the plugs starting to foul. I was also told that PCV replacement is a 5 hour job and awkward. I have the factory service manual but I can't find how to do the replacement. Is this diagnosis correct and any hints or tips you can provide will be helpfull. Ta!