Airspeed & Throttle Flight-Beheaviour

Hey, I had posted a earlier about some airspeed and throttle issues. Airspeed I still have no consistency in this issue. I am flying mostly with the PX4-Airspeed sensor und use the Holybro Pixhawk 6X Flightcontroller. I have set up the same in a different Plane/VTOL and there I have consistend airspeed and throttle beheaviour. But sometimes when I have more then 3m/s sink i get the issue but I also discovered that even if I try to fly without the Airspeed Sensor ( FW_ARSP_MODE = 1 (Do not use airspeed in controller)) and set the Throttle Trim FW_THR_TRIM = 0.4 (40%) it does absolutely do not behave how it should be, it seems to be it uses some random values to control the plane. How can I fix the issue or how should I set the parameters so that I hav none of this issues?