Yes, the battery has been disconnected a few times after changes were made to the configuration. The P1300 and P0172 codes come back consistently.Yes, the engine is running with too much fuel and therefore tries to reduce it by adaption.
Has battery been disconnected after other fuel pressure regulator has been installed to reset adaption values?
I'll check all of the above tomorrow, these are definitely worthwhile suggestions.there was another thread were there was suspicion that vacuum could/might pull fuel over EVAP tube. It would make sense in that way that in vacuum conditions you get much more fuel, adapt to -25..-50% and as soon as you enter boost area there is no more addtional fuel, but adaption still reduces fuel by 25...50%, which is too much, engine goes lean and stalls.
If long term adaption also applies during start (I am not 100% sure about that) better starting behavior with disconnected tube is also explainable: usually you would have 3 bar differential pressure, but with disconnected tube you will have 3.5....3,8 bar, resulting in square root (3,5/3) or square root (3,8/3) 8...12% more fuel which partyl compensates -25% long term adaption.
Proposal for further tests:
1. check fuel pressure (although they might be ok). engine running, tube disconnected, should read 3bar.
1b. check for residual pressure. engine stopped, turn ignition on, fuel pressure should jump to 3 bar, turn ignition off, fuel pressure should very slowly drop to minimum 2.2 bar within 20 minutes, if everything is ok it remains nearly constant within an hour. this could rule out dripping injectors.
2. disconnect EVAP, put a short rubber fuel tube on the throttle connector, plug the open end with a screw, fix the screw with clamp. Take care that the lose EVAP line does not interfere with the belt. disconnect battery for 60s to reset adaptions values. check driving again.
check oscillating front O2 sensor again. In first post it was ok, but fuel trim were both?? around 0, later on both fuel trims -25, O2 sensor still oscillating or flat at 0,7..0,8V. (Although I do not see a direct connection between working and defect O2 sensor and boost/vacuum conditions). (Just in case: do not use any contact spray on the O2 sensor connector, it will destroy the sensor).