Airplane Sway In Top-Down Game

Hello, i'm Trying to create Top-Down Game

i'm trying to make my Airplane Sway to left and right when mouse moving

here is my Sway Script :

     public var MoveAmount : float = 1;
      
     public var MoveSpeed : float = 2;
      
     public var AirPlane: GameObject;
      
     public var MoveOnX : float;
      
     public var MoveOnY : float;
      
     public var DefaultPos : Vector3;
      
     public var NewGunPos : Vector3;
     
     
 function Start () {
 DefaultPos = transform.localPosition;   
 }
 
 function Update () {
         MoveOnX = Input.GetAxis("Mouse X") * Time.deltaTime * MoveAmount;
      
     MoveOnY = Input.GetAxis("Mouse Y") * Time.deltaTime * MoveAmount;
      
     NewGunPos = new Vector3 (DefaultPos.x+MoveOnX, DefaultPos.y+MoveOnY, DefaultPos.z);
      
     AirPlane.transform.localPosition = Vector3.Lerp(AirPlane.transform.localPosition, NewGunPos, MoveSpeed*Time.deltaTime);
 }

for somehow this script make my airplane Jumping its like swaying Up not to the left or right.

how i make it sway in Z axis ?