Okay so I have a 2001 LS430 I get a hard start sometimes and when I'm driving and I go full throttle it will backfire through the exhaust and the car will loose power. The cat's have been gutted cause the driver side cat came apart. So p0420 is on no big deal there. I am also getting a bank 2 sensor 2 oxygen sensor code. The car has 252k on it. The idle is perfect on it, it just seems to lack power in normal driving conditions and under full throttle. Any and all help would be fantastic.

 

Try clean/ replace the MAF ?

 

Maf is good

 

Your gutted cats are causing turbulence with the back pressure its called the venturi effect and/or it could be all the codes that would make the car go into limp mode.

 

So install pipe for 3rd cat and high flow cats in place of upstream cats should fix everything right.