2-3-1 Code despite new O2 sensors,plugs, cap, rotor etc..

[UncleBoost]

<----------Still at it Huh!



Ok.....Now I am really stumped.
I will try to keep this to a minimum.
Been battling this monster since I bought it
96 850 turbo wagon 188k miles when bought, now 228k.
New Platinum Plugs, Cap, Rotor, O2 sensors front and rear, Idle Air control valve, Temp sensor.

Was getting 212, 153. Changed Front O2 sensor on 12/01/04. System reduced to 1 code 153 (Rear O2 Code) Changed Rear O2 Sensor, cleared codes under the Hood. (Not with a code scanner) drove for 12 miles code Free, No Check engine light. on the 13th mile "BLING"! here that Amber
B!tch (sorry) is again with another Code. 2-3-1. Too lean or Rich at part load Stage 1???? WHat the hell is part load stage 1? I know too lean could be caused by a vacuum leak but I have checked all that and can find No leaks. It burns pretty clean now since the Temp sensor incident so I don't think its burning Rich at least not to the smell and without hooking up an exhaust gas analyzer I wouldn't know for sure. What could it be?
Could the cat be damaged? I did see alot of tiny white grainy Pebbles inside the Rear After Cat O2 sensor lodged inside the 3 fins of the sensor.
Could these some of the cat coming apart? or is it part of the internals of the O2 sensor that may be trying to escape?. Since replacing the O2 sensors, the 212 and 153 codes have vanished could it be that now that both have been replaced, it is more accurately analyzing the system and now gives me this new 2-3-1 code? WHats next?

I spent all day saturday replacing a leaky OIL FEED pipe on my 88 745Ti.
Felt good to have reduced from 5 oil leaks down to 1 now. And its not fair that my 96 850 has more miles than my 88 740...
The 740 stayed broken most of the time, seems like the 850 is trying to do the same. I own 3 volvos and have twins. I ain't scared of NOTHING!
ha hahaaaa...(Mental) <----See what long term Volvo use does to the mind.
Thanks.