This script causing a moving brick using Tweens doesn't work. Can someone fix this?

I have this script here and I wanna know why the part flies away! Ive tried replacing with waitforchild() but that didnt work. Im trying to make a random meter that varies in value.

--Services
local TS = game:GetService("TweenService")
local RS = game:GetService("RunService")
local HS = game:GetService("HttpService")

--Definers
local part = script.Parent.SpawnTherm:WaitForChild("Moving")


while wait(4) do
    --Defining Tables and Table Editing
    local mathRandom = math.random(2.5, 4)
    local goal = Vector3.new(0.7, mathRandom, 0.05)
    local tweenInfo = TweenInfo.new(
        4,
        Enum.EasingStyle.Cubic,
        Enum.EasingDirection.Out,
        0,
        false,
        0
    )


    while wait(1) do
        part.Position = Vector3.new(part.Position.X, part.Position.Y, part.Position.X)
        wait(0.05)
    end

    local Tween = TS:Create(part, tweenInfo, {Size = goal})
    Tween:Play()
end