Bad 02 censors are a P0051 code. Had that come up several times in my first 2013 5.0. Only modds was a H-pipe, GT500 muffs, 85mm TB, and SCT canned tune. The 02's will not heat up fast enough or got overheated and now function incorrectly. But P219A is def not 02's 100% not. Vacuum or exhaust, check, then check your memory for any recent overspeed runs where your rpm went above 7000 rpm (6850 rpm is the 5.0's oem cutoff) and 7000 rpm is usually apart of canned tunes such as the SCT canned strategy tunes. You have to have a custome tune to bump your rpm limit up over 7000 rpm as far as I can tell.