I gotta pipe up and say the upstream O2 sensors probably weren't bad, but the vacuum leak caused the codes in the first place. Oreilly's and Advance started an urban legend when they were scanning cars that O2 sensors frequently go bad, and I'm doing what I can to combat it. DO NOT REPLACE O2 SENSORS WHEN BOTH BANKS BEGIN READING LEAN AT THE SAME TIME!!!! "They've been fine for 150,000 miles, now they both went out in the last seven minutes...what a coincidence."