This CFrame script isn't working properly, how can I fix it?

I recently found this script that makes Roller Coasters completely coded on it's own physics, and it works great, except for one thing. Once the coaster finishes its run, it teleports to a different node on the other side of the map, instead of just starting the coaster run again. The script is here:

Functions = {}
Train=0
PosToNeg1=false
PosToNeg2=false
PosToNeg3=false
PosToNeg4=false
OPosToNeg1=false
OPosToNeg2=false
OPosToNeg3=false
OPosToNeg4=false
Coaster=script.Parent
PointsGroup=Coaster.Points
Points=Coaster.Points:GetChildren()
Speed=0
DifferenceBetweenPoints={5,5,5,5}
CurrentTrackNumber={14,11,9,6}
CurrentTrack={PointsGroup:FindFirstChild("14"),PointsGroup:FindFirstChild("11"),PointsGroup:FindFirstChild("9"),PointsGroup:FindFirstChild("6")}
PreviousTrack={PointsGroup:FindFirstChild("13"),PointsGroup:FindFirstChild("10"),PointsGroup:FindFirstChild("8"),PointsGroup:FindFirstChild("5")}
CurrentPosition={0,3,1,4}

Functions.MoveCar = function(Car)
	Train=script.Parent.Train
	Speed=script.Parent.Speed.Value
	script.Parent.CurrentTrackNumber.Value=CurrentTrackNumber[1]
	if Speed>0 then
		PosToNeg1=false

		if OPosToNeg1==false then
			CurrentTrackNumber[1]=CurrentTrackNumber[1]+1
			PreviousTrack[1]=CurrentTrack[1]
			CurrentTrack[1]=PointsGroup:FindFirstChild(CurrentTrackNumber[1])
			CurrentPosition[1]=CurrentPosition[1]+DifferenceBetweenPoints[1]
			OPosToNeg1=true
		end
		if OPosToNeg2==false then
			CurrentTrackNumber[2]=CurrentTrackNumber[2]+1
			PreviousTrack[2]=CurrentTrack[2]
			CurrentTrack[2]=PointsGroup:FindFirstChild(CurrentTrackNumber[2])
			CurrentPosition[2]=CurrentPosition[2]+DifferenceBetweenPoints[2]
			OPosToNeg2=true
		end
		if OPosToNeg3==false then
			CurrentTrackNumber[3]=CurrentTrackNumber[3]+1
			PreviousTrack[3]=CurrentTrack[3]
			CurrentTrack[3]=PointsGroup:FindFirstChild(CurrentTrackNumber[3])
			CurrentPosition[3]=CurrentPosition[3]+DifferenceBetweenPoints[3]
			OPosToNeg3=true
		end
		if OPosToNeg4==false then
			CurrentTrackNumber[4]=CurrentTrackNumber[4]+1
			PreviousTrack[4]=CurrentTrack[4]
			CurrentTrack[4]=PointsGroup:FindFirstChild(CurrentTrackNumber[4])
			CurrentPosition[4]=CurrentPosition[4]+DifferenceBetweenPoints[4]
			OPosToNeg4=true
		end
		DifferenceBetweenPoints[Car]=(CurrentTrack[Car].Position-PreviousTrack[Car].Position).magnitude
		CurrentPosition[Car]=CurrentPosition[Car]+Speed
		if CurrentPosition[Car]>=DifferenceBetweenPoints[Car] then
			if CurrentTrackNumber[Car]<#Points then
				CurrentTrackNumber[Car]=CurrentTrackNumber[Car]+1
				PreviousTrack[Car]=CurrentTrack[Car]
				CurrentTrack[Car]=PointsGroup:FindFirstChild(CurrentTrackNumber[Car])
				CurrentPosition[Car]=CurrentPosition[Car]-DifferenceBetweenPoints[Car]
			else
				CurrentTrackNumber[Car]=1
				CurrentTrack[Car]=Points[1]
				PreviousTrack[Car]=Points[#Points]
				CurrentPosition[Car]=1
			end
		end
		

		Train:FindFirstChild("Car"..Car):SetPrimaryPartCFrame(PreviousTrack[Car].CFrame:Lerp(CurrentTrack[Car].CFrame,(CurrentPosition[Car]/DifferenceBetweenPoints[Car])))
	
	end
end

return Functions

If anyone could help me, that would be great! I'm not very good with these kinds of things.