error codes... OBDII

[seraslibre]

I got the following codes pulled from my 99' 4-cyl camry w/ 100k mi. Its surging/hesitating when pulling off from a stop, mostly after the engine warms up. I replaced the upstream O2 sensor, TPS, ETC and spark plug wires. The spark plugs were replaced about 20k mi ago, but were subject to the readings of a dead O2 sensor for about 3k mi., so they had a bit of carbon build-up on them when i pulled them off.

..finally..here are the codes:
P0171: Bank 1 lean
P1133: HO2S Insufficient switching sensor 1/bank 1 , fuel control shifted lean.


by the way, the car isn't running lean, its running rich, if anything, since my fuel economy has gone downhill.

Is this a possible symptom of a bad downstream O2 sensor?
Any help and/or advice will be greatly appreciated.

[OEMonkey]

Is this a possible symptom of a bad downstream O2 sensor?

if yer talking about the o2s after the cat, then the answer is no. post cat o2 has nothing to do with afr. its just there to monitor the cats efficiency if its doing its job or not.
if your ho2s signal is always at low voltage and not switching properly and averaging 4.5v, pcm will remain in open loop even when the cars warmed up. when in open loop, you run rich. when the ho2s signal is always lean, pcm command would be opposite(you run rich). a good o2s will be switching .1-.9v(lean, rich, lean, rich). if its not switching, it will throw a code.
test the o2s and find out whats causing excess 02 emissions.