I think Hetfield was stating that a severe leak can cause stalling, AS WELL as cause the 1151, which would answer the "will an O2 sensor cause stalling" question. They phrased they were getting an 1151.. NOT that they KNEW the O2 was bad.. going solely off of a code, you can't assume anything, and I would lean towards an induction leak, as well, to cause both the stalling, and the lean code.
Ray