I have Vaux-Com but didn't think to try it, tomorrow I will. I also got the same O2 readings using Multiscan on Saab.
STFT is +23%, injectors 3 mS, MAP 39kPa, it is going into closed loop, have not checked fuel pressure but regulator is not leaking - checked with Mityvac.Engine runs smooth and I have used Smoke-Pro on intake and it is airtight.
I thought that if the ECU was seeing 350mV it would add fuel to richen hence +23% STFT and because the ECU does not see the O2 voltage increase it just keeps adding fuel?

Martin.