I should add that I had a similar issue on an 05 STi, though not as drastic(~2 & ~10) and it wound up being the cam gears. Bother were replaced and the car ran fine. Occasionally I see silly readings if, after flashing the ecu, the gas pedal is touched within the first 45 seconds or so of start up. The ecu does need to figure itself out after a flash. Not sure if any of this helps, but I hope so!