Ahhhhhhhhh the dreaded P0016.
Supposedly the learning values can get way off in the ECU and there is no way to reset it which necessitates the ECU replacement. I remember somebody allegedly put a different ECU in his car then switched back and it fixed itself or something. It was a long time ago.
Here is a long read on it. It has bitten an unfortunate many.
https://www.ft86club.com/forums/showthread.php?t=123459