I would reduce the ultra low latency mode to around 10-15 range, it makes the FFB loop most stable for iRacing. Then I would also add a little bit more damping.
it could also oscilate due to setting the gain setting inside your game.
Why don’t you try the easy mode ? https://www.youtube.com/watch?v=BxDw6lRWMs0 nice video to help you a bit with the settings but it is for the pro model.