Here's just a snapshot of a log I took while this was happening... I didn't get a log when it hit low 13's/high 12's and went to open loop, but when this trip started AFR and targeted AFR were in the mid 14's. In the log it is now at around 13.7, this was about 1.5 hours into highway cruise.
http://www.datazap.me/u/wepeel/cruise?log=0&data=1