Custom character controller randomly rotates after colliding with an object

My character controller after colliding with an any object adds continuous rotation on the y.

I have no idea whats happening...

Motor Script:

 using UnityEngine;
 using System.Collections;
 using System;
 
 [RequireComponent(typeof(Rigidbody))]
 public class FirstPerson3DMotor : MonoBehaviour {
 
     private Rigidbody rb;
 
     private Vector3 _velocity = Vector3.zero;
     private Vector3 _rotation = Vector3.zero;
     private Quaternion targetRotation;
     private float camRotation;
     private float currentCameraRotationX = 0f;
 
     private float rotationLimit = 80f;
 
     private Camera cam;
 
     // Use this for initialization
     void Start () {
         rb = GetComponent<Rigidbody>();
 
         cam = GetComponent<FirstPerson3DController>().playerCamera;
     }
 
     // Fixed Update is called every time a physics event (iteration) occurs.
 
     void FixedUpdate ()
     {
         ApplyMovement();
         ApplyRotation();
     }
 
     void ApplyRotation()
     {
 
         rb.MoveRotation(rb.rotation * Quaternion.Euler(_rotation));
 
         if (cam != null)
         {
 
                 currentCameraRotationX -= camRotation;
                 currentCameraRotationX = Mathf.Clamp(currentCameraRotationX, -rotationLimit, rotationLimit);
 
                 cam.transform.localEulerAngles = new Vector3(currentCameraRotationX, 0f, 0f);
 
         }
     }
 
     void ApplyMovement()
     {
         if (_velocity != Vector3.zero)
         {
             rb.MovePosition(rb.position + _velocity * Time.fixedDeltaTime);
         }
     }
 
     public void Move(Vector3 velocity)
     {
         _velocity = velocity;
     }
 
     public void Rotate(Vector3 rotation)
     {
         _rotation = rotation;
     }
 
     public void RotateCamera(float cameraRotation)
     {
         camRotation = cameraRotation;
     }
 
     public void Jump(float jumpHeight)
     {
         if(Input.GetKeyDown(KeyCode.Space))
         {
             rb.velocity.y.Equals(jumpHeight);
         }
     }
 }

Controller Script:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 [RequireComponent(typeof(FirstPerson3DMotor))]
 public class FirstPerson3DController : MonoBehaviour {
 
     //used to represent the speed the character walks.
     [Header("Movement Settings")]
     public float walkSpeed = 2.0f;
 
     //Used to represent their speed while sprinting.
     public float moveSpeed;
 
     //Used to represent look sensitivity for the camera.
     public float lookSensitivity = 10.0f;
 
     //Used for setting the jump height
     public float jumpHeight = 4f;
 
     //Used to represent if the player can sprint or not. 
     //(Usage: if the player is hurt and they cannot sprint).
     public bool canSprint = true;
 
     //Used to represent weather the player's footsteps can be heard.
     [Header("Sound Settings")]
     public bool soundEnabled = true;
 
     //used to represent the clip-clop sound of footsteps.
     [SerializeField]
     private AudioClip footStep1;
 
     [SerializeField]
     private AudioClip footStep2;
 
     [Header("HUD Settings")]
     public bool enableHUD = true;
     public GameObject reticle;
     public bool hideReticle = false;
     
     [Header("Player Camera")]
     public Camera playerCamera;
 
     private FirstPerson3DMotor fpsMotor;
 
     private bool isSprinting;
     private bool isJumping;
 
     private GameObject playerHud;
 
     // Called when the game starts.
     void Start () {
 
         /*Setting FPS Motor equal to the the object this 
         scripts attached to's version of the FPS Motor Object. */
         fpsMotor = GetComponent<FirstPerson3DMotor>();
 
         playerHud = GetComponentInChildren<Canvas>().gameObject;
 
         Cursor.visible = false;
 
         HUDConfigure();
 
         Physics.gravity = new Vector3(0, -20.0F, 0);
 
         moveSpeed = walkSpeed * 1.5f;
     }
 
     void HUDConfigure()
     {
         if (enableHUD == false)
         {
             playerHud.SetActive(false);
         }
 
         if(hideReticle == true)
         {
             reticle.SetActive(false);
         }
     }
 
     void HideCursorListener()
     {
 
         if(Input.GetKeyDown(KeyCode.Escape))
         {
             Cursor.visible = true;
         }
 
         if (Input.GetMouseButtonDown(0))
         {
             Cursor.visible = false;
         }
 
     }
 
 
     void CheckIfSprinting()
     {
         if (Input.GetKeyDown(KeyCode.LeftShift) && canSprint == true)
         {
             isSprinting = true;
         }
 
         if(Input.GetKeyUp(KeyCode.LeftShift))
         {
             isSprinting = false;
         }
 
     }
 
     void CalculateMovementVelocity()
     {
         float xMove = Input.GetAxis("Horizontal");
         float zMove = Input.GetAxis("Vertical");
 
         Vector3 movHorizontal = transform.right * xMove;
         Vector3 movVertical = transform.forward * zMove;
 
         Vector3 velocity;
 
         if (isSprinting == false)
         {
             velocity = (movHorizontal + movVertical) * walkSpeed;
         }
         else
         {
             velocity = (movHorizontal + movVertical) * moveSpeed;
         }
 
         fpsMotor.Move(velocity);
 
         if (Input.GetKeyDown(KeyCode.Space))
         {
            GetComponent<Rigidbody>().AddForce(Vector3.up * jumpHeight, ForceMode.VelocityChange);
         }
 
 
 
     }
 
     void CalculateRotation()
     {
         float _yRot = Input.GetAxisRaw("Mouse X");
 
         Vector3 _rotation = new Vector3(0f, _yRot, 0f) * lookSensitivity;
 
         //Apply rotation
         fpsMotor.Rotate(_rotation);
 
         //Calculate camera rotation as a 3D vector (turning around)
         float _xRot = Input.GetAxisRaw("Mouse Y");
 
         float cameraRotation = _xRot * lookSensitivity;
 
         //Apply camera rotation
         fpsMotor.RotateCamera(cameraRotation);
     }
 
 
     void Update () {
 
         CheckIfSprinting();
 
         CalculateMovementVelocity();
         CalculateRotation();
 
         HideCursorListener();
         
     }
 }

Thanks in advance :)

Also disregard the is kinematic tick box being clicked I did that for debugging purposes.