What I've done so far, yesterday and the day before:
- Replaced engine air filter & cabin air filters
- Changed oil (and oil filter)
- Replaced both upstream O2 sensors
- Replaced serpentine belt & its tensioner
- Cleaned the throttle body
- Cleaned the MAF sensor
- Replaced spark plugs
- Replaced intake manifold gaskets
P0420 went off again anyway... I've scheduled an appointment at the nearby dealership for a diagnostic. I don't know if I can take this camping tomorrow (2 hrs there) or if I should just use a different vehicle this weekend. At least I haven't seen any pending or logged misfires today. I'm out of my depth here, had to get friends to help me with half of what I've done to it, and there's only one thing I haven't tried yet that I know I can do with the tools available to me (except replacing the coil packs but I've heard those are expensive.) That's unplugging the battery for a bit to force the ECU to relearn things from scratch - but I've heard from a friend that may cause problems with the radio? I've got the stock radio still, do y'all know if disconnecting the battery causes any kind of anti-theft BS with it? I don't see anything about that in the manual.
