Unslide does not revert back to normal

I know that a lot of questions alike to this have already been asked, but my problem is that when the player stops sliding, the character controller either (A) grows to a size less than the original, or (B) falls through the floor (because the bounds of the controller's collision pass through the ground). Here is my code:

 if (isSliding)
     {
     tempCenter.y = controller.height/4;
     controller.center.y = tempCenter.y;
     //controller.center.y = 0.25;
     controller.height = 0.5; // height is slide height
     moveDirection.z = 2.0; // speed is slide speed
     controller.Move(moveDirection * Time.deltaTime);
 
     slideTimer += Time.deltaTime;
     if (slideTimer > slideTimerMax) //stop sliding (part I need help with)
     {
         isSliding = false;
         moveDirection.z = 3.0; //speed is normal
         transform.position.y += 10;
         controller.center = Vector3(transform.position.x,0.5,transform.position.z);
         //tempCenter.y = controller.height/4;
         //controller.center.y += 5.0;
         //controller.center.y = tempCenter.y;
         controller.height = 1.0;
     }
 }
 if (!isSliding)
 {
     speed = 3.0;
     controller.Move(moveDirection * Time.deltaTime);
 }

All of the lines of code that were commented out are different approaches I have tried to use. No matter what value I set (high/low, pos/neg, mult/div) I always end up with a smaller position on the y axis than what I started with. Help would be greatly appreciated as I cannot figure out how to solve the problem.