How to make a part follow player on only a specified axis?

So i want this part i named "straszak" spawn and follow player on one axis once it spawned.

local plr = game.Players.LocalPlayer
repeat wait() until plr.Character
local char = plr.Character
while wait(120) do
	if workspace:FindFirstChild("straszak") == nil then
		if math.random(1,2) == 1 then -- 50% chance
			local straszakclone = script.straszak:Clone()
			straszakclone.Parent = workspace
			coroutine.wrap(function()
				while wait() do
					local vector, onScreen = workspace.CurrentCamera:WorldToViewportPoint(straszakclone.PrimaryPart.Position)
					if onScreen == true then
						print("onscreen") 
					elseif onScreen == false then
						print("offscreen")
					end
				end
			end)()
			coroutine.wrap(function()
				while wait(5) do
					straszakclone:SetPrimaryPartCFrame(char.HumanoidRootPart.CFrame*CFrame.new(Vector3.new(6,0,22.5))) -- it resets position every 5 seconds
				end
			end)()
			local CF = straszakclone.PrimaryPart.CFrame
			while wait() do
				straszakclone:SetPrimaryPartCFrame(CFrame.new()) -- i want it to follow player only on one axis
			end
		end
	end
end

here's a visual representation on what i want