Object controlled by accelerometer: speed slows when further from target point, how do I increase the speed when phone is tipped in opposite direction?

Hi!

I've written a C# script that controls an object's movement based on the accelerometer values (for an endless runner game). I've calculated the percentage the object is away from the centre point, and currently use this line:

 speedX = speedX - (SpeedSlow()/100 * speedX) +0.3f;

to set the speed of the object to be faster when close to a set centre point, and slower as it moves away from this transform position.

The problem I'm having is that I want the speed to slow down as the object moves towards the edge (which it does): but when you tip the phone the opposite direction to bring the object back towards the centre point, I want the speed to be set immediately faster (and this is the part I can't work out how to achieve).

I tried stating:

 if (speedX < 0.2f)
     {
     transform.position = Vector3.MoveTowards(transform.position, targetBagPos, Time.deltaTime * 3.5f);
 }

But this doesn't work: it causes the movement to behave erratically, and moves the object in the opposite direction on the x axis than expected (right when the phone is tilted left etc)

This is the script with the problematic line commented out:

 using UnityEngine;
 using System.Collections;
 
 public class Accelerometer : MonoBehaviour {
     
     public Vector3 targetBagPos;
 
     void Update () 
     {
         float tempx = Input.acceleration.x;
         float tempz = Input.acceleration.z + 0.7f;
         float speedX = 6.0f;
 
         speedX = speedX - (SpeedSlow()/100 * speedX) +0.3f;
 
         //        if (speedX < 0.2f)
         //        {
         //            transform.position = Vector3.MoveTowards(transform.position, targetBagPos, Time.deltaTime * 3.5f);
         //        }
 
         transform.Translate(tempx * Time.deltaTime * speedX,0,0);
         Vector3 posX = transform.localPosition;
         posX.x = Mathf.Clamp (posX.x, -1.5f, 1.5f);
         transform.localPosition = posX;
         
         transform.Translate(0,0,-tempz  * Time.deltaTime * speedX);
         Vector3 posZ = transform.localPosition;
         posZ.z = Mathf.Clamp (posZ.z, -1.5f, 1.5f);
         transform.localPosition = posZ;
 
         SpeedSlow();
     }
 
     public float SpeedSlow()
     {
         float maxDistance = 1.5f;
         Vector3 currentPos = this.transform.localPosition;
         Vector3 centrePos = new Vector3(0,0,0);
 
         Vector3 distanceBetween = centrePos - currentPos;
         float length = distanceBetween.magnitude;
 
         float perCent = length / maxDistance * 100;
 
         Debug.Log (perCent);
 
         return perCent;
     }

Does anyone have any ideas on ways I could script the movement so that when the object is tilted back towards the centre point: the speed is immediately given an increase.

I hope I explained that clearly enough!

All the best, Laurien