BMW 620 GT with ruckeln / drop off when starting, replacement gearbox for the cat *Video*

Hello, I’m getting tired of doing belly dancing exercises with my 620s. It just jerks at the start, at 1000-2000 rpm. It feels like the gas would stay away for a short time or like when the clutch presses briefly in the manual gearbox in the acceleration process. The link to the video:https://youtu.be/wTjbQ95dHR8?si=eUM75Pg3zUGEzRtG That’s not a gear change that does it; with everyone starting, first the ruckler steps on then the gear change. eim DonSimon replaced in August due to a different defect of the torque converter, then we thought that this error was from the gearbox, then he installed an exchange gearbox. Briefly puked as we buried an additional 1900€. The same phenomenon still exists. Second attempt at the BMW dealer, there we left 600€ for the diagnosis “no idea”. (among other things nothing special in the error memory) It also feels minimal as if the gas was with slow acceleration it occurs at 1000-1400 rpm With stronger acceleration it occurs at 1700-2000 rpm. I give myself the ball soon and hope you can help me… Greetings Zib