Driving along the road that connects these cities I found an amount of waterfalls which names I always failed to know. Three of them are powerful enough to have one, and I guess that two may be Gufufoss and Múlafoss but I’m not sure of it. I can’t identify your Gufufoss with any of them. I found the waterfalls departing from Egilsstaðir in the order they are shown.
The World of Waterfalls has been to this waterfall, which you can read about here.