Thanks T4R for all the helpful information. I've been all over this forum for the last few days working on ideas on how to build up and fix this new to me 2003 4Runner. It drives so great despite having far too many miles on it; 316,000.
I'd been itching for a 4Runner for far too long to handle hunting and future (but not too soon) daddy things but didn't want to get into a new monthly bill. I'd been bugging my wife about it for far too long, enough that she even started looking around to help me out and found this one. We found it in Atlanta for about $4500 that ended up needing a bit of exhaust and brake work but seems to be mostly rust free or at least nothing serious. I was able to get into it without spending too much more than my old car was worth so it was a dead trade after selling off my last ride.
Sadly, she just threw the P0420 code last weekend that I'll be working through. This forum has been exceptionally helpful in diagnosing the issue. Hopefully it'll just be the downstream bank 1 O2.
I've had an incredibly hard time not spending the money for a Prinsu rack and good LED bar and making cosmetic changes. SO many ideas and mods but repairs come first. Thanks again T4R.