Hey guys, I'm wondering if doing a good ol' Italian tuneup might be worthwhile for my 2004 2.7L. I've been throwing a P0420 code for a few years now, and now I can't even clear it without it coming back very soon. I have a bad/clogged cat according to the shop. My fuel economy is poor. I want to trade it in/sell it in a few months so I'm thinking about throwing some premium gas and fuel injector cleaner in and taking her out for the tune-up. I'll clear the codes, get her warmed up, WOT it to redline, shift, WOT to redline, repeat. I'll do this a few times up and down the highway to see if I can't clear some gunk out of my cat and keep my codes clear. My resale value is shot if I can't fix this issue. Anyone have any experience with this? Problems? Tips? Thanks.