Z22SE Strange warm start and poor idle

Hey there,

already asked a few questions here, but seems i'm not able to get the problems fixed myself by research.

I drive an Astra G convertible built 2005 with a z22se engine. The egr is blinded by the manufacturer already and i changed the cooling temperature sensor and read out the air intake sensor and map sensor by obd. Values seem to be ok. No luck with the temperature exchange.

My problems and actual situation: Cold start is very good. Starts and runs fine goes down to 750 rpm. Then the rpm drops and varies about 25 rpm and sometimes more and sounds like the engine will turn off but keeps running then. The more electrically things i turn on the lower the rpm gets. The engine doesnt get the rpm higher automatically. Dont know if this is normal but seems wrong to me. With lights on and only heating (no air condition) it drops to about 650 rpm and the instrumental lights begin to flicker hard.

Then i turn the engine off and try to restart it with the engine warmed up, the engine starts instantly but starts at 100rpm and goes stuttering up to idle rpm. Hope you can understand what i mean. I have bo idea what the problem could be with this two things.

Timing chain and water pump is new since 6000km and makes absolutely no noise.
If you need something to help me identify the problem just ask!

Hope my englisch isn't too bad -

Greetings from germany!
I had similar issue with mine less than few weeks ago. Swapped Crank sensor / plugs / Coolant temp sensor, then the issues proceeded in the end i got a good fuel rail with a FPR in it and a recon Starter motor, once these have been swapped I have not had a warm starting issue. Might be worth looking at the Crank sesnor and starter motor ? If you swap the starter motor might as well do the sensor as its in the same area.

I hope this helps.
Thanks for your reply. Ordered a crank sensor today to get that possibility out of the way. The starter motor works well i think, cause there is no misfire as it cranks well and directly. Already thought about the fuel rail / a leaking injector or fuel pressure regulator. I'm not very firm with engines and only do this to learn something and safe money, so this was the last thing i wanted to do when there is no other possibility left :(
I will keep you informed what happens after crank sensor exchange and maybe also upload a video of the behavior of the engine.