How can I rotate an object with random speed with some intervals ?

Code (csharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5.  
6. public class Turn_Move : MonoBehaviour {
7.    public int TurnX;
8.    public int TurnY;
9.    public int TurnZ;
10.  
11.    public int MoveX;
12.    public int MoveY;
13.    public int MoveZ;
14.  
15.    public bool World;
16.  
17.    // Use this for initialization
18.    void Start () {
19.  
20.    }
21.  
22.    // Update is called once per frame
23.    void Update () {
24.        if (World == true) {
25.            transform.Rotate(TurnX * Time.deltaTime,TurnY * Time.deltaTime,TurnZ * Time.deltaTime, Space.World);
26.            transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.World);
27.        }else{
28.            transform.Rotate(TurnX * Time.deltaTime,Random.Range(3,300) * Time.deltaTime,TurnZ * Time.deltaTime, Space.Self);
29.            transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.Self);
30.        }
31.    }
32. }
33.  

This is the random part :

Code (csharp):

1.  
2. Random.Range(3,300)
3.  

but sine it's changing the random numbers too quick the changes are almost not visible. I want somehow to make that if for example the next random will stay for example 5 seconds at this speed number then move to the next random number and again stay at this number 5 seconds and so on.

Tried this :

Code (csharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5.  
6. public class Turn_Move : MonoBehaviour {
7.    public int TurnX;
8.    public int TurnY;
9.    public int TurnZ;
10.  
11.    public int MoveX;
12.    public int MoveY;
13.    public int MoveZ;
14.  
15.    public bool World;
16.  
17.    private bool IsGameRunning = false;
18.  
19.    // Use this for initialization
20.    void Start ()
21.    {
22.        IsGameRunning = true;
23.        StartCoroutine(SpeedWaitForSeconds());
24.    }
25.  
26.    // Update is called once per frame
27.    void Update () {
28.  
29.    }
30.  
31.    IEnumerator SpeedWaitForSeconds()
32.    {
33.        var delay = new WaitForSeconds(3);//define ONCE to avoid memory leak
34.        while (IsGameRunning)
35.        {
36.            if (World == true)
37.            {
38.                transform.Rotate(TurnX * Time.deltaTime, TurnY * Time.deltaTime, TurnZ * Time.deltaTime, Space.World);
39.                transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.World);
40.            }
41.            else
42.            {
43.                transform.Rotate(TurnX * Time.deltaTime, Random.Range(3, 300) * Time.deltaTime, TurnZ * Time.deltaTime, Space.Self);
44.                transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.Self);
45.            }
46.  
47.            yield return delay;//wait
48.        }
49.    }
50. }
51.  

but that just rotate the object once each 3 seconds. and not rotating it all the time with speed changing every 3 seconds.

but now it's not rotating for 3 seconds it rotating every 3 seconds.

better to describe what I want is like intervals. The object should spin all the time nonstop like i Update but then each 3 seconds to change for a random speed.

for example spin at speed 5 ....after 3 seconds spin at speed 77 ....after 3 second spin at speed 199

 

Wrote in notepad really quick so it's untested:

Code (CSharp):

1. using UnityEngine;
2. public class Turn_Move : MonoBehaviour {
3.    public int TurnX;
4.    public int TurnY;
5.    public int TurnZ;
6.    public int MoveX;
7.    public int MoveY;
8.    public int MoveZ;
9.    public bool World;
10.    private float rotationTime = 0; //Used to track how long its been spinning for since the last reset
11.    private float rotationDuration = 3f; //How long should it rotate for before changing rotation speed again?
12.    private int rotationSpeed = 0;
13.  
14.    // Use this for initialization
15.    void Start () {
16.       rotationSpeed = Random.Range(3, 300);
17.    }
18.    // Update is called once per frame
19.    void Update () {
20.  
21.  
22.        if (World == true) {
23.            transform.Rotate(TurnX * Time.deltaTime,TurnY * Time.deltaTime,TurnZ * Time.deltaTime, Space.World);
24.            transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.World);
25.        }else{
26.            transform.Rotate(TurnX * Time.deltaTime, rotationSpeed * Time.deltaTime,TurnZ * Time.deltaTime, Space.Self);
27.            transform.Translate(MoveX * Time.deltaTime, MoveY * Time.deltaTime, MoveZ * Time.deltaTime, Space.Self);
28.        }
29.  
30.        //Reset rotation speed every 3 seconds
31.        rotationTime += time.deltaTime;
32.        if (rotationTime > rotationDuration){
33.            rotationSpeed = Random.Range(3, 300);
34.            rotationTime = 0;
35.        }
36.    }
37. }

Edit: forgot to reset rotationTime at end