I can't get my fpc to keep it's momentum

I created an fpc that wont be effected by gravity when it enters a trigger, but I can still use wasd to move around, and the character doesn't keep it's momentum. So I just need to be able to float through the zero gravity area and not be able to control you're movement.

     public float speed = 10;
 
     public Rigidbody rb;
     public Vector3 jump;
     public float jumpForce;
     public bool jumping;
 
     public Transform ground;
 
     public static int pauseNo;
 
     // Use this for initialization
     void Start () {
         Cursor.lockState = CursorLockMode.Locked;
         rb = GetComponent<Rigidbody>();
         jump = new Vector3(0.0f, 2.0f, 0.0f);
         jumpForce = 2.0f;
         jumping = false;
         pauseNo = 1;
     }
     
     // Update is called once per frame
     void Update () {
         float transltaion = Input.GetAxis("Vertical") * speed;
         float straffe = Input.GetAxis("Horizontal") * speed;
         transform.Translate(straffe *Time.deltaTime, 0, transltaion *Time.deltaTime);
 
         if (Input.GetKeyDown("escape"))
         {
             if (pauseNo == 1)
             {
                 Cursor.lockState = CursorLockMode.Confined;
                 speed = 0;
                 pauseNo -= 1;
             }
             else
             {
                 Cursor.lockState = CursorLockMode.Locked;
                 pauseNo = 1;
                 speed = 5;
             }
         }
 
         if (Input.GetKeyDown("space") && jumping == false){
             rb.AddForce(jump * jumpForce, ForceMode.Impulse);
             jumping = true;
         }
 
         if (Input.GetKey("left shift") && jumping == false)
         {
             speed = 10;
         }
         if (Input.GetKeyUp("left shift") && jumping == false)
         {
             speed = 5;
         }
     }
 
     void OnTriggerEnter(Collider other)
     {
         if (other.name == "noGrav")
         {
             GetComponent<Rigidbody>().useGravity = false;
         }
         if (other.name == "ground")
         {
             jumping = false;
         }
     }
 
     private void OnTriggerExit(Collider other)
     {
         if (other.name == "noGrav")
         {
             GetComponent<Rigidbody>().useGravity = true;
         }
     }
 }