I did a flight with the FSLabs A319 on JoinFS and a mate of me too.
And we both had the same problem, that sometimes we had FULL deflection of the Ailerons for no reason!
The nose pulls up very much and the autopilot disconnects.
Every time, when I connect JoinFS to my P3D I get randomly this issue, and when I disconnect JoinFS, no problem occurs.
Can you imagine, what this problem is? Perhaps can you do something to fix this?
Random issues with joinFS
Re: Random issues with joinFS
Do you have ATC mode enabled in the JoinFS settings? Try disabling that, as it interferes with the simulator's AI system.