Got a Camry 2005 4 cyl, with 140k miles on it. Seeing blue smoke at cold start lately (not always), but the car is perfect otherwise. Did the BG EPR/MOA cleaning, and then changed the PCV valve, but the problem is still there. Is it the stem valves? In that case, since it is a very hard DIY, should I sell the car or keep it running for another year or so until it dies on me?