1984 Mercury Cougar LS - return line question

So when it gets really hot outside, if I leave the my car in the sun for like 30 minutes to an hour, if I then turn it back on it either runs really rough or stalls. I'm pretty sure it is vapor lock due to heat soak, and I want to install one of those fuel vapor separators. It's been carb swapped and currently doesn't use a return line, but I know you can reuse the low pressure fuel pump that came with the car which I know has a return line. So I went under my car to look at the tank and saw a hose next to the fuel line that has been cut off and pretty much want a confirmation on if the hose in the picture is the return line or some other hose without a purpose.