Seke wrote: ↑Sat Sep 07, 2019 3:10 pm
It goes really lean and at 3.5k rpm and 0.3 bar of boost the ve is over 200 to keep it at lambda 1.
That's better. It appears a settings change has corrected the readout and you're not going lean (by data indication).
So now back to your stumbling, which appears similar to dropping a cylinder. While it could be anything at this point (always keep an open mind), I would attempt to isolate the issue. For example, when it is held running rough, check the exhaust headers with an IR temp gun to (hopefully) find one that is dropping and causing the jittery readings.
If that isolation is successful, then you can further focus your attention there, first checking everything mechanical (valve seal/lash, timing, spark plug(s), manifold seals, leak-down, etc) and electrical (spark, timing, ignition coil(s), wires, connections, injector(s) etc) that impacts it.
Good luck, and if you take this path report whatever you find … or don't.
David