'99 V6, rich front/rough idle+shift

[ptrimby]

'99 Camry, v6, ~120k mi, College student (ie frugal , mostly bikes around now)

First symptoms: Pulsating (lightly slipping clutch feel) at certain in 4th gear when low rpm.
Current: Same pulsating whenever at certain throttle point (park/neutral or any gear). Startup is bogged, then Rough/missing idle. When started cold, continues to upshift late (even past open/closed loop changeover); if engine restarted after full warmup, shifts normal (retains some rough running).

In post-possible-fix test drives, following have shown up a few times each (in random other than misfires appearing all at same time).

Flash MIL light 3x now (twice after ~1 min warmup, once under accel uphill in test)
p0120 TPS circuit malfunction
p0302 Misfire #2
p0304 Misfire #4
p0306 Misfire #6
p0171 Lean/too much oxygen #1 bank
P1153 A/F Sensor Circuit Response Malfunction (Bank #1 Sensor #2)


So far -
On all below, checked input/supply voltage, all OK

* MAF: checked, resistance possibly ~.5kOhm off (low), but response correct; cleaned, no change; duct is snug to manifold
* Throttle body: cleaned
* Acoustic flow vacuum controlled thingus on intake manifold: OK
* TPS: checked with multimeter, scan tool, best of knowledge OK
* PCV: was a bit sticky, replaced
* Sparks: checked cables OK, replaced plugs NGK ***Front bank running quite rich (carbon black plugs), rear bank good (possibly every so slightly lean, light grey) - yes plugs were and are correct
* A/F - 02 sensors:
o Front (Bank#2Sensor#1) - heater @ 0.8 to 1.0 Ohm
o Rear (B1S1) - heater @ 0.8 to 1.0 ohm
o Cat (B1S2) - have not fished under seat/console yet
* Fuel inject/rail equip: visual inspect OK, connectors snug - some acorns around rails though...

B1S1 A/F-O2 replaced ~8k ago, OEM part, dealer install, w/timing belt change as well - problem began appearing slowly after this (approx 8 months)

Here is my confusion: Getting misfire codes on #2 bank, which corroborates with running rich/missing as per all 3 spark plug appearence on #2 bank - this would lead to lean condition on an O2 sensor if missing - yet so far has shown lean on B1S1 A/F and the post-cat B1S2 O2. RPM dropping, rough engine at ~1/4 throttle could be TPS failing to switch from idle to main injection...but that doesn't seem to float well with the whole Rich bank2.

Current thoughts lead me to try replacing B2,S1 A/F (front), then if no-go the (B1,S2) O2 (post-cat)...looking for any other suggestions - PCM?

And so people don't post all confused about "what bank? what sensor?": http://www.*******.com/fsm/2000/Serv...yl%20Ident.pdf

[Eye8Pussies]

check for vacuum leaks