My E53 3.0i just threw the P1093 code. Just like OP, I used valvoline 5w30 restore and protect the last oil change, about 2500 miles ago.

LTFT's on both banks are between -3 and -4%.
MAF reads over 4gm/s at idle, which from my research, is a little higher.
O2 sensors V on both banks both pre and post are according to spec, except for bank 2 post O2 sensor fluctuates between 0.7 and 0.75 where as bank 1 is constant at 0.77.

I am considering to replace the MAF before I replace the O2 sensors. I hope it is not the CATs.

If the cat was bad, wouldn't you get a catalyst low efficiency code and not P1093? This sounds like a vacuum leak or maybe a bad injector. Try swapping the bank 1 and 2 injectors and see what happens. Removing the injectors isn't too difficult, the most annoying part is getting the injector electrical connectors loose.

I think it's pretty rare to get a cat efficiency code. Mixture codes, especially with older vehicles, are often a combination of issues which is why sometimes even a small change of one of the factors can be enough to bring the mixture back within limits for turning the CEL on.