Recently converted a 99 vette “12584929” OS to a 02 “12212156” OS. Transferred most setting over from previous tune. Every thing works except commanded AFR suddenly drops to 11.70 about 2/3rds thru a quarter mile run, and remains at 11.70 until the end of the run. Wideband O2 confirms the drop. Can’t find anything in the tune that should cause this, and it didn’t occur in the previous tune. B1208, B3603, B3605, B3618 & B3659 are all well above 11.70 where this occurs. I am sure I am missing something, but can't find it. Some help would be appreciated. Thanks.