Unstable AFR on idle

hello,

I started to tune a Bmw e36 325i turbocharged engine, while the idle rpm varies 200 rpms the AFR is very unstable. We tested for any air leaks nothing appeared. The AFR sits between 11.4 and 15 randomly!

Link G4+

Timing on idle is 12"

What shall I do?

Is it a fairly agressive cam? Is it jumping from a cell with higher numbers than the one beside it? Just looking at the obvious things first. Thats quite the swing.

It has a mild cam profile, and the cells surrounding the target idle cell were adjusted properly for interpolation! And still it is very fuzzy