Rigidbody Addforce not working as expected ( video included)

When grounded my vehicle moves rather slow

When slightly off of the ground I get the same results as if grounded

Lifted off the ground slightly more the vehicle accelerates like 10 time more the normal rate.

Heres a video

 if(rocketBoo)
         {
             if (timerReset) 
             {
                 
                 TimerReset ();
                 timerReset = false;
 
             }
                 
             Invoke ("Timer", 0.001f * Time.deltaTime);
 
             ground = false;
             Debug.Log ("go!");
 
             Camera.main.transform.eulerAngles = new Vector3 (0,0,Random.Range(0,shake));
 
             if(timer >= chargeTime)
             {
 
                 Vector3 rocketDirection = Vector3.Lerp (minY.transform.position,maxY.transform.position,0.1f);
                 this.GetComponent<Rigidbody2D> ().AddForce ((rocketDirection - this.transform.position) * rocketBoost, ForceMode2D.Impulse);
             
             }
 
             if(timer >= accTime)
             {
                 Vector3 rocketDirection = Vector3.Lerp (minY.transform.position,maxY.transform.position,0.1f);
                 this.GetComponent<Rigidbody2D> ().AddForce ((rocketDirection - this.transform.position) * acceleration, ForceMode2D.Impulse);
 
             }
 
             if(timer >= stopTime)
             {
                 Camera.main.transform.eulerAngles = new Vector3 (0,0,0);
                 TimerReset ();
                 rocketBoo = false;
 
             }
         
         }