There is no 4" lifts for a 2wd.
There are only 3" lifts. Like a spindle lift if it works on your type of sport or a body lift or a torsion twist but thats all you really can do on a 2wd besides getting something custom built. You could also try a company named Camburg here in So. Cal. they make a 5-6" kit for the edge but it might work on the explorer you will have to call them and ask.