What airspeed are you taking off at and what VS are you using with what flap setting? A stall is generally simply not enough speed for the current vertical climb.
I note that you are engaging your auto pilot after takeoff but remember that even when you activate A/P 10 seconds after take off, A/P captures your current speed and current climb.
If, for example, you rotated at 130knts but you were accelerating to 180knts for your climb to 8000ft and your vertical speed is a good climb for 180knts; let’s say you engage A/P for speed and you were only at 140knts, the auto pilot will capture that 140knts and immediately reduce your thrust but you’re still in a climb good for 180knts. A stall is imminent. This was just an example. Better advice can be given once you provide your settings.