Have you check if there is no conflict in your axes settings (TrackIR axis set as the same as the joystick or something like that)
You could also consider to monitor your curves of the joystick (option panel)
Have you the same problem with other module? (Or are you flying only DCS-World)
Please, post your configuration (CPU, GPU, RAM, OS (32 or 64bits), Joystick, TrackIR/FacetrackNoIR present or not,... That may help.