turn on and off character controller

I have tried and tried to get a script working where if the character controller is not touching anything, it will get destroyed and turn into rigidbody with a sphere collider. Then if the collider is touching the ground (a completely flat surface) the sphere collider will get destroyed and the character controller will get turned on. This works, but for some reason, the sphere and the character are never completely touching the ground because they switch back and forth with both functions activating simultaneously. My code is posted below. How could I fix this problem? Thanks for any help. I have been stuck for days!

 var sc : SphereCollider;
 var ch: CharacterController;
 var Mode = 3;
 var Mode1 = 1;
 var newTime = 0.0;
 var StartTime = 0.0;
 
 function Update(){
         StartTime = Time.time;          
           var    controller : CharacterController = GetComponent(CharacterController);
     if(Mode == 3 && !controller.isGrounded){
               print("this");
                   newTime = Time.time;
                   Mode = 4;
               
       }
       if(Mode!=3 && controller.isGrounded){
               print("else");
               newTime = 10000;
               Mode = 3;
       }
 
       if(Time.time - newTime > .1 && Mode == 4){
                 go();
         }  
 }
 function go(){
     print("2");
         var walkscript: FPSWalkeriPhone = gameObject.GetComponent(FPSWalkeriPhone);
         walkscript.enabled = false;
         var    controller : CharacterController = GetComponent(CharacterController);
         Destroy(controller);
         sc = gameObject.AddComponent ("SphereCollider");
     //    Mode = 3;
 }
 function stop(){
     print("3");
     
     if(Mode ==4){
         print("mode4");
         var newcollider: SphereCollider = GetComponent(SphereCollider);
           Destroy(newcollider);
          var walkscript: FPSWalkeriPhone = gameObject.GetComponent(FPSWalkeriPhone);
         walkscript.enabled = true;
         ch = gameObject.AddComponent ("CharacterController");
         var    controller : CharacterController = GetComponent(CharacterController);
         controller.height = 1.5;
         Mode = 3;
     }
 }
 function OnCollisionStay ( colInfo : Collision ){
     new WaitForSeconds(.1);
     for ( var contact : ContactPoint in colInfo.contacts ) {
         // If we're actually touching the ground, not just some wall.
         if ( Vector3.Angle ( contact.normal, Vector3.up ) < 45 ) 
         {
             print("collisionstay");
         //    rigidbody.velocity.y = 0;
               stop();                              
         }
     }
 }