FPS Controller flying off in the air?

I'm using two combination of scripts for this controller, but first of all the problem.

The problem is when I look all the way down at the floor and move backwards the controller flys up into the air, this also applies when I look up and walk forwards, how cna this be fixed?

GIF OF PROBLEM: https://gyazo.com/f670b140aedc2e15c730364bc6b65c41

Walking Script

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. public class PlayerController : MonoBehaviour {
5.     public float defaultmoveSpeed = 8.00f;
6.     public float moveSpeed = 8.00f;
7.     public float jumpSpeed = 15.00f;
8.     public float gravity = 20.0f;
9.     public float sprintSpeed = 16.00f;
10.     private Vector3 moveDirection = Vector3.zero;
11.     private CharacterController playerController;
12.     // Use this for initialization
13.     void Start () {
14.         playerController = GetComponent<CharacterController>();
15.     }
16.  
17.     // Update is called once per frame
18.     void Update () {
19.         //Movement Section
20.         playerMovement();
21.         //methods to which should only be used when player is grounded
22.         if (playerController.isGrounded)
23.         {
24.             jumpMethod();
25.         }
26.    
27.     }
28.     public void jumpMethod()
29.     {
30.         moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
31.         moveDirection = transform.TransformDirection(moveDirection);
32.         moveDirection *= moveSpeed;
33.         if (Input.GetButtonDown("Jump"))
34.             moveDirection.y = jumpSpeed;
35.     }
36.     public void playerMovement()
37.     {
38.         moveDirection.y -= gravity * Time.deltaTime;
39.         playerController.Move(moveDirection * Time.deltaTime);
40.         if (Input.GetKey("w"))
41.         {
42.             transform.Translate((Vector3.forward) * moveSpeed * Time.deltaTime);
43.         }
44.         if (Input.GetKey("S"))
45.         {
46.             transform.Translate((Vector3.back) * moveSpeed * Time.deltaTime);
47.         }
48.         if (Input.GetKey("A"))
49.         {
50.             transform.Translate((Vector3.left) * moveSpeed * Time.deltaTime);
51.         }
52.         if (Input.GetKey("D"))
53.         {
54.             transform.Translate((Vector3.right) * moveSpeed * Time.deltaTime);
55.         }
56.         // Sprint key function
57.         if (Input.GetKey("left shift") && Input.GetKey("w"))
58.         {
59.             moveSpeed = sprintSpeed;
60.         }
61.         else
62.         {
63.             moveSpeed = defaultmoveSpeed;
64.         }
65.     }
66. }

Looking around Script

Code (CSharp):

1. using UnityEngine;
2.  
3. // Very simple smooth mouselook modifier for the MainCamera in Unity
4. // by Francis R. Griffiths-Keam - www.runningdimensions.com
5.  
6. [AddComponentMenu("Camera/Simple Smooth Mouse Look ")]
7. public class SimpleSmoothMouseLook : MonoBehaviour
8. {
9.     Vector2 _mouseAbsolute;
10.     Vector2 _smoothMouse;
11.  
12.     public Vector2 clampInDegrees = new Vector2(360, 180);
13.     public bool lockCursor;
14.     public Vector2 sensitivity = new Vector2(2, 2);
15.     public Vector2 smoothing = new Vector2(3, 3);
16.     public Vector2 targetDirection;
17.     public Vector2 targetCharacterDirection;
18.  
19.     // Assign this if there's a parent object controlling motion, such as a Character Controller.
20.     // Yaw rotation will affect this object instead of the camera if set.
21.     public GameObject characterBody;
22.  
23.     void Start()
24.     {
25.         // Set target direction to the camera's initial orientation.
26.         targetDirection = transform.localRotation.eulerAngles;
27.  
28.         // Set target direction for the character body to its inital state.
29.         if (characterBody) targetCharacterDirection = characterBody.transform.localRotation.eulerAngles;
30.     }
31.  
32.     void Update()
33.     {
34.         // Ensure the cursor is always locked when set
35.         Screen.lockCursor = lockCursor;
36.  
37.         // Allow the script to clamp based on a desired target value.
38.         var targetOrientation = Quaternion.Euler(targetDirection);
39.         var targetCharacterOrientation = Quaternion.Euler(targetCharacterDirection);
40.  
41.         // Get raw mouse input for a cleaner reading on more sensitive mice.
42.         var mouseDelta = new Vector2(Input.GetAxisRaw("Mouse X"), Input.GetAxisRaw("Mouse Y"));
43.  
44.         // Scale input against the sensitivity setting and multiply that against the smoothing value.
45.         mouseDelta = Vector2.Scale(mouseDelta, new Vector2(sensitivity.x * smoothing.x, sensitivity.y * smoothing.y));
46.  
47.         // Interpolate mouse movement over time to apply smoothing delta.
48.         _smoothMouse.x = Mathf.Lerp(_smoothMouse.x, mouseDelta.x, 1f / smoothing.x);
49.         _smoothMouse.y = Mathf.Lerp(_smoothMouse.y, mouseDelta.y, 1f / smoothing.y);
50.  
51.         // Find the absolute mouse movement value from point zero.
52.         _mouseAbsolute += _smoothMouse;
53.  
54.         // Clamp and apply the local x value first, so as not to be affected by world transforms.
55.         if (clampInDegrees.x < 360)
56.             _mouseAbsolute.x = Mathf.Clamp(_mouseAbsolute.x, -clampInDegrees.x * 0.5f, clampInDegrees.x * 0.5f);
57.  
58.         var xRotation = Quaternion.AngleAxis(-_mouseAbsolute.y, targetOrientation * Vector3.right);
59.         transform.localRotation = xRotation;
60.  
61.         // Then clamp and apply the global y value.
62.         if (clampInDegrees.y < 360)
63.             _mouseAbsolute.y = Mathf.Clamp(_mouseAbsolute.y, -clampInDegrees.y * 0.5f, clampInDegrees.y * 0.5f);
64.  
65.         transform.localRotation *= targetOrientation;
66.  
67.         // If there's a character body that acts as a parent to the camera
68.         if (characterBody)
69.         {
70.             var yRotation = Quaternion.AngleAxis(_mouseAbsolute.x, characterBody.transform.up);
71.             characterBody.transform.localRotation = yRotation;
72.             characterBody.transform.localRotation *= targetCharacterOrientation;
73.         }
74.         else
75.         {
76.             var yRotation = Quaternion.AngleAxis(_mouseAbsolute.x, transform.InverseTransformDirection(Vector3.up));
77.             transform.localRotation *= yRotation;
78.         }
79.     }
80. }
81.