I'd start by making sure it actually has enough coolant in it since you said a hose blew off it. After making sure it has enough coolant look at the coolant elbows, belt tensioner and waterpump. When i got my car a couple years ago I also had to replace my radiator and the way your describing it is similar to my issue how if I would go 65 the low coolant light went away, all it was for me was the coolant was actually low