This has been a problem since launch, way back last year.
Throttle input is maintained by A or B on the controller - the problem, however, is it rapidly changes the VS of the aircraft in an unnatural way. Throttle Increase (Small) is slightly better, but it is open to the same rapid changes. Any increase on the throttle pitches the nose of the aircraft in almost unrestricted climb, the same in descent (but reversed). It’s all happening far too quickly to react in a natural way to trim the aircraft appropriately.
With the Xbox version launching soon, this has been a problem since the sim released. Will it be fixed?
It’s all set to the default bindings. Increasing throttle with A sends the VS and nose of the aircraft climbing at an unrealistic and unrestricted pitch - far too sensitive. B for decrease does the opposite, but it still remains.
I also never experienced that problem using an Xbox controller (though I usually use a separate throttle and yoke now, my last use while remote desktop’ing was last week and I had no problems with the throttle on the Xbox controller then).
Keep in mind that MSFS has an “acceleration” system for button inputs where sometimes if you tap a button multiple times, or hold it down, the change rate on each button press will suddenly increase by 10x until you stop pressing buttons for a bit.
So this can affect throttle when pressing it many times or for a long time, but this affects many inputs not just throttle.
It’s not broken. I think you have a keybind issue somewhere.
I too use an XBox controller (or I did until recently when it began having connection issues due to a loose wire near the strain relief) and never had this problem. I’m now using a Logitech F310 mapped the same way as the XBox.
Although I mostly use my Bravo TQ I still have the A, B and A+B mapped on the controller and they work as they should, even being double mapped with the BTQ. I keep them mapped on the controller because I use the R/L Triggers on it for ground rudder control. Using the A, B and A+B for throttle control along with the Y, Y+B for brake and parking brake make taxiing so much easier than anything I’ve been able to do with the Honeycomb Alpha and Bravo.