desastersoft addon help needed

[U505]

since I have installed the add on of desastersoft I have noticed when i am above 250 km my bf 109 E3 or E4 begins to move upwards and downwards.i have tried to set off all realism options thinkings it was caused by air turbulence or something else but it didn't have any effects.I tried also to close the water cooling system but the plane continues to jump up and down.did someone have the same problem and solve it ? i would appreciate help because it is difficult to play in that conditions especially when you have to shot down ennemies planes.