S70 was (is) Idling fine til it warms up then craps out on me. Starts again after 1/2 dozen tries. idles ok then just dies. I replaced the Cat Converter and the same PO422,102, and 171 codes keep coming up. Anybody got a clue. O2 sensor? Which one? Upstream or downstream? I don't wanna put too much more into this car just to get it running.

 

P0102 is MAF issue; have you tried cleaning it?

P0171 could also be related to a MAF issue. Ck for vac leaks downstream of MAF?

I would also ck your fuel pressure; your fuel pump starting to fail (or fuel pump relay) could possibly cause these symptoms...

 

I had a similar problem and it turned out the fuel pump relay was going bad. easy one to test also.
Just pull the fuel pump relay and short the connections for pins 15 and 87 with a paperclip or some such device.
in my case it fired up and ran fine with the relay out and the pins shorted.

it seems that the fuel pump will fire up for a second when you first turn your car even if the relay is going bad, in which case it turns right back off.

I don't think this is your problem but like i said, it's an easy test to eliminate it as the cause....

 

the code po102 on autodata comes up with wiring short to earth,maf.vaf sensor,ecm
po171 system to lean, bank 1 / intake/exhaust leak,air system,maf/vaf sensor,vuel pressure/pump,injector(s),h02s