[afstud]

Ok i have a 2007 328i Hard top Vert with 95k miles on it. I had the Notorious High pitched howling as the PCV failed on the valve cover along with rough running and P0012 code. Replaced the Valve cover and cleaned the Vanos Solenoids. tested, drove it around for a few hours and everything was beautiful, no more problems since and she runs much nicer. couple days later i get the P0012 code again so i cleared it to see if it and when it would come back, few more days later CEL came on again and this time its P0015. Another thing that happens is Very randomly when i come to a stop the RPMs will drop and then go back to normal and its so quick then it doesnt happen till about the next time i drive the car or after that and its only once. What would be the best course of action to do with this? i know the codes but dont want to just start throwing parts at it without some confidence. TIA!