Take the car on the road and drive under a bit of load for a while watch what the pre cat lamda is doing, make sure its still switching and not going to the weak side.

A steady high reading from the post cat lamda say 0.7 volts or above is saying that the cat is efficient ..not so much rich Malcomn but low of oxygen (effects of good cat burning oxygen up)

If it was rich the pre cat lamda would report it, assuming that if fuel trims are good at base 0 they are reporting a weak trend.

I tend to take the scanner out on the road now in the vehicle and watch what lamdas are doing under load, sat in the workshop they can show good switching , under load can be a different story.

Try giving air flow meter hot wire a clean with brake cleaner.