The title pretty much sums it up. I had p1170 with an occasional p1173 until it finally ate my cats. Replaced the cats with a magnaflow ypipe and put new Bosch front o2's in. Was codeless for a while. Now the codes seemed to have swapped.

I did a smoke test before replacing cats and fixed the leak I found.

My mpg has been crumby for a while and I have a rough idle so I'm starting to wonder if it's time for a new MAF?