Toyota Repair: Toyota Camry engine/sensor problems, spark coils, intake leaks

Question
My car is a Toyota Camry '98 V6 3.0litre engine
Well I had couple engine problems recently primary showing codes: P0155 and P1300.
The engines didnt work regulary, sometimes stops with no symptoms that could indicate it will happen, and sometimes I could not start the engine for 5 minutes.
I get couple spare parts, so this what I replaced:
PCM-engine control computer, all 3 spark coils (sparks were changed 2months ago), I changed igniter, and almost all peoblems dissapear.
The problem codes were read by mechanic before I did any changes.
Now I got my private OBD reader with live data and most things looks ok, however there is one small problem
LTFT B2 has reading of -17.97% at all times, no matter what.
Short and long fuel trim for bank 1 sensor 1 are changing all the times and look fine to me.
O2S 11 - is around 0.97V, O2S 21 - is around 0.46V.
Well maybe Im wrong but acording to car manual, O2 sensor for bank 2 is located in front of the engine, I replaced with another one and nothing happened. The readings didnt changed even while I disconnected O2 sensor.
The other thing is, should I get any codes from computer when system shows abnormal behave like this?
I dont get any codes now....
Could you tell me what are your thought on that?
I would be grateful for any help.
Kind regards,
Patrick

Answer
Yes, bank 2 is near the radiator, The fuel trim is way off, this can be caused by a vacuum leak or air leak on the intake so be sure to check for this, with the FT this far out of specs it seems that there should ve a check engine light.
After verifying that there are no intake leaks the next thing would be to check the basic engine timing, if the timing is off there may be a problem with the timing belt, it may be poose or worn causing the belt to have jumped one tooth or more on the bank one cam.
The fuel trim readings are usually not cuased by the sensor but something else that is making the computer go to a too rich or lean condtion, in this case too rich.  It may also be a good diea to hook up a vacuum gauge to see what the intake manifold vacuum is.