The trick to a wall is to get the airplane to pass through flying on the wing to 3-D or vectored thrust mode immediately.
The fact that the plane stalls one wing and snaps indicates that your problem is that you're stalling *only* one wing. You need them both to stop flying at the same time.
Some things to try :

42 degrees of throw isn't enough for all plane types. Try increasing your throw. I have a cap that will do the same thing with less than 55 degrees of throw.

Your elevator servo(s) may be too slow to get the plane to transition abruptly enough from flying to vectoring. Try faster servos.

Try doing the wall inverted. The rudder will remain more effective at stabilizing the plane inverted. You also might have more elevator throw inverted.


Have you verified that your plane is properly laterally balanced and that both elevator halves move the same amount?


Moving your CG rearward increases the effectiveness of the elevator servos and can also help you get the plane to pitch both wings past stalled quickly enough.