Broken code, need help tonight if possible please

So if you add this to a player, and move around, it kinda flashes between where its suppoosed to be and somewhere else. i want it to make the camera move between a top down view and a behind view, depending on the mouse y axis. so if the mouse moves down, it will become top down. but only move as much as the mouse moved, hence the delta i added in.

 using UnityEngine;
 using System.Collections;
 
 public class CameraController : MonoBehaviour {
     
     public float Sensitivity;
     public float MaxDistance;
     public float MaxAngle;
     private float MouseY;
     private float MouseYSet;
     private float CameraAngleX;
     private float PlayerHead;
     private float PlayerBack;
     
     private float CameraY;
     private float CameraZ;
 
     public GameObject CameraTarget;
     
     void Start () {
         PlayerHead = CameraTarget.transform.position.y + CameraTarget.transform.lossyScale.y / 2;
         PlayerBack = CameraTarget.transform.position.z - CameraTarget.transform.lossyScale.z / 2;
     }
     
     void Update () {
         // Look controls
         MouseY -= Input.GetAxisRaw ("Mouse Y");
         CameraAngleX = Mathf.Clamp (CameraAngleX + (MouseY - MouseYSet) * Sensitivity * 10, -MaxAngle, MaxAngle);
         CameraY = Mathf.Clamp (CameraY + (MouseY - MouseYSet) * Sensitivity * 10, CameraTarget.transform.localPosition.y, PlayerHead + MaxDistance);
         CameraZ = Mathf.Clamp (CameraZ + (MouseY - MouseYSet) * Sensitivity * 10, PlayerBack - MaxDistance, CameraTarget.transform.localPosition.z); 
         if (MouseY != 0)
         {
             transform.localRotation = Quaternion.Euler (CameraAngleX, transform.localRotation.y, transform.localRotation.z);
             transform.localPosition = new Vector3 (transform.localPosition.x, CameraY, CameraZ);
             MouseYSet = MouseY;
         }
     }
 }