That's actually a bit lean. No way Shinji is targeting that, unless he was trying to make you a pretty extreme economy map. Next thing I'd look at is AF Learning 1, and AF Correction 1. With a steady 15.5 AFR at cruise, I'd expect these to be high positive. AF Learning 1 maxes out at 15%, and Correction at 25%.
If these are pegged or close to it, your car has a large air leak and is dumping fuel to compensate. A 15.5 AFR means it's run out of room to adjust and still can't hit target, which should be in the 14.2-14.7 range. That, or one of the sensors (front O2 or MAF) responsible for closed loop fueling has gone bad.
Hopefully that's all it is, because it's a simple fix.