Volvo OBD II codes

[Rayg1124]

My Volvo V70 XC 2001 has been having random idle issues. Dying, sputtering, erratic idle, and a very rich exhaust. No check engine light initially. I changed spark plugs, cleaned MAF sensor, and put some ISO-HEET in my gas. I thought the HEET fixed my problem.

When driving to work today at highway speeds I felt some sputters, a considerable loss of power, elevated gas consumption, and check engine light came on. When I got to a stop light my car sputtered and died. I restarted it, no throttle power. Waited a few minutes then barely had enough power to get into parking lot before died again.

Check engine light is giving off 4 codes, 3 of which are pending.

The codes are as follows, with descriptive links under each one:

1174
1171 (pending)
http://www.troublecodes.net/volvo/c70-s ... 1998-2008/

0171 (pending)
https://www.dmv.de.gov/services/Vehicle ... c_list.pdf

0134 (pending)
https://www.obd-codes.com/p0134


I am leaning towards replacing my front 02 sensor considering the 0134 code. Can someone let me know if this sounds like a good idea? My center exhaust muffler is also quite rusted, but I am thinking to replace that after 02 sensor.

Thanks!