Please Help Code still Remains p0420.
(2007 Camry CE)
Nothing else is wrong with the car but I loose gas with a 4 cylinder engine and loss of power.

I’ve changed the catalytic converter , manifold exhaust, both oxygen sensors , replaced the muffler Bank 1 pipe, changed all spark plugs and ignition coils. I really like the car and it is a very dependable car but I’m lost on how to get rid of this code problem. Please help

 

What does the exhaust color look like? Tail pipe look sooty? I'm wondering if something else is making the car rich/lean.

 

It’s been a year since I changed it it seem like the same color when I bought it brand new. Should I change the fuel injectors ?

 

I doubt your fuel injectors are bad, the car would really struggle to even start if that was it. Usually changing a cat or O2 sensor fixes this issue. It really seems like you are running rich- poor gas mileage, loss of power.
Vacuum leaks would be the next thing I would rule out. Heck, you've changed everything else.