Randomly lean?
 

I´ve got a 1990 1.6 MX running MS1 (MSPNP), LC1 and IAT (MAF delete).
I loaded the basemap, bought tunerstudio, set up a little rich AFT-target table and started tuning. Got my idle nice and stable and WUE works good too. No problem starting either.

On Saturday I went for a long drive. Use VE analyzer to autotune. Quite happy with the result I stopped the car and waited 16 hours before I took another run. Not that long, but AFR was still good. Then I waited 4 hours and too another run (evening). This time the AFR was good at idle, but when I started driving and WUE was completed, the AFR wen lean! I had to stop the car and change the VE-table to be able to drive home safely.

The question is. Why? MAT / CLT correction? This was a cold evening. The CLT was about 85c (185 F). And the IAT-sensor showed 12 C (53.6F). So if I understand correctly, MAF / CLT correction is not what made it go lean. Or am I wrong?

Edit: What? My WUE is under 100% Hmmmmm.. This must be causing me problems?

ASE is typically under 100%; WUE should not be.