Without ignition control you should disable the ignition timing base idle control as it can slow down the idle motor a bit. You find it under Extras->ignition settings advanced.
I was afraid that the dual stall behaviour could happen with the new settings. A log would help but I suspect that we can drop the "Idle afterstart RPM, value added" value down to 100 again. I we probably need some code tweaking before an high afterstart rpm will work properly, at the end of the period the rpm target seem to be lowered suddenly instead of fading out.
Under Extras-> Idle settings Advanced, we find "Assymetric PID conf", try setting that to enabled. IIRC this fairly undocumented feature will make the PID more responsive to low rpm then it is to high rpm.
Then there is a setting that I don't find any definition for in a stepper application. It's under Extras->idle settings general and is called "Idle actuator speed/PWM frequency". It should be set to 6 or 7, yours is currently set to 0.
