OBD2 fault code P0027

Proper diagnostic should be done before replacing parts. For the mass air flow sensor code and fuel trim I would have suspected a dirty throttle body plate and plugged up pcv system. To verify you need the proper equipement and tools to look at some vehicle parameters and an understanding of what you are looking at so chances are, you replaced a good working mass air flow sensor. Fault codes only give you an idea as to where to start looking for a fault and other components related to that fault. For a fault with PO27, a few things you need to check. One is how often do you change your oil and really be honest about it. Sludge will cause the camshaft reset valve to stick as well cause the pcv system to plug up and get the throttle dirty because of it. So your problems could have being related? If oil quality is not an issue how is your oil pressure? An internal oil leak will cause low oil pressure. Usually leaking oil pick up tube seals will cause the pressure to drop enough to affect the operation of the reset valve since it uses oil pressure to control the timing. Usually running the vehicle for about 15-20 minutes and pulling the oil dipstick out while vehicle is running, if you see air bubbles in the oil you have leaking oil pump pick up tube seals and you will need to fix that first before doing anything else. If that is ok, you need to verify that the timing belt has not jumped a tooth or two. To verify, turn engine by hand and see if the crank and cam timing marks line up. If they do not, replace the timing belt, tensioner, and roller. If that is ok you now have narrowed the problem down to either the camshaft reset valve or the variable timing hub. I would replace the reset valve first since it is the easiest and cheapest fix to start with. Hope this info helps you and if you have any questions let me know.