Good, glad to see your getting purged out of what you see on forums saying to screw with MAF and VE tables when as you saw it just blurs the results in scanner data and gets you no where to having clear fuel trims.

You cannot blindly use cells 0 to 19 as a bulk value since some cells are used for decel and fuel learn is off thus your trim average is bloated since its adding into the trim average when PCM is commanding fuel off thus would be leaner on decel but being added to when fuel is commanded on