Anbodyy help with my car gas system I am working on?

So im trying to make a car that needs gas, but theres some thing that are hard to do, any help? Heres my code, the problems are it keeps making the value go down even when your not holding any buttons, any help?

local UserInputService = game:GetService("UserInputService")

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local hum = player.Character:WaitForChild("Humanoid")
local fill = script.Parent
local stamina = 100
local canRun = true
running = false

UserInputService.InputBegan:connect(function(key, gameProcessedEvent)
    if not gameProcessedEvent and canRun and key.KeyCode == Enum.KeyCode.W or key.KeyCode == Enum.KeyCode.A or key.KeyCode == Enum.KeyCode.S or key.KeyCode == Enum.KeyCode.D then
        running = true
        while running and stamina > 0 do
            fill:TweenSize(UDim2.new(stamina * 0.01, 0, 1, 0), "Out", "Quad", 0.5)
            stamina = stamina - 3
            wait(0.5)
        end
    end
end)


UserInputService.InputEnded:connect(function(key, gameProcessedEvent)
    if not gameProcessedEvent and key.KeyCode == Enum.KeyCode.W or key.KeyCode == Enum.KeyCode.A or key.KeyCode == Enum.KeyCode.S or key.KeyCode == Enum.KeyCode.D then
        running = false     
    end
end)

while true do
    if not running and stamina < 100 then
        fill:TweenSize(UDim2.new(stamina * 0.01, 0, 1, 0), "Out", "Quad", 0.5)
    end
    if stamina >= 33 then
        canSprint = true
    elseif stamina == 0 then
        canSprint = false   
    end
    wait(0.5)
end