catalytic 0421 cat

I see that this topic has been addressed previously, but not very recently, so maybe there's a new solution by now. My 2002 P5, 189K miles, shows P0421 code indicating a poorly performing pre-cat. I tried CataClean and the isolating the rear 02 sensor, both of which did nothing to improve things...

I just got a PO421 for the fourth time and finally, i am giving into the fact that i cant just keep resetting my cel. I need to do something about it. What have you all done to make this problem go away? I'm thinking of just going cat-less soon, so is there a way i can relay the catalytic O2...

Last month I threw a 0300 CEL in my 2003 P5 (stock) with the (seems like) standard crappy misfiring performance that goes along with it. I was getting bogging down on hills, stuttering at idle, loss of power on acceleration and then sudden lurches forward as the car seemed to catch up with...