I have an old X45 stick throttle combo which I have never been able to use with FSX or P3D. The problem being: In the centre position the smallest possible movement either gives too much climb or too much decent..........1mm of movement gives either +1500 or -1500 rate of climb. Up and down like a yo-yo. Level flight was almost impossible even with the in game sensitivity settings at 1.
I did ask around on several forums for a solution a few years back but no one seemed to have an answer, one or two folk did have the same problem though. Anyway I've finally found a solution: In the [CONTROLS] section of the config file I have added STICK_SENSITIVITY_MODE=0 . It works in P3D but I haven't tried it in FSX although I'm sure it will work.
The in game sensitivity settings can then be used effectively. Mine are now up near the max.
Not sure what it does but the stick is much better. Flight is no longer a roller coaster.