How to open list of urls one by one in firefox

I have a list of urls in a txt or csv file.

https://superuser.com/users/1277284
https://superuser.com/users/1327728
https://superuser.com/users/3577284
…..

Now I want to open every link in same tab and wait 2-3 seconds between each link. I’m unable to do this with iMacros as my Mac doesn’t support it.