I've been working my way through the prolegomena of an Old Testament theology from an evangelical scholar. He devotes about twenty pages to surveying the various methods that have been proposed in the past two hundred years on the aforementioned subject. While reading this I realized that precious few scholars (and evangelicals are not excluded here) have taken seriously the analogia fidei as the principle rule for all Old Testament exegesis. In other words, there are few who believe that the Old Testament records serve as a legitimate witness to Jesus of Nazareth and the gospel of his kingdom...at least in a manner that can be treated in scholarship.
Attempting to go beyond Jesus the Son of God in order to establish a doctrine of God (yes, even Israel's God) is not just a methodological error...it's blasphemy. Paul (speaking by the very Spirit) says that the eternal God has given a commandment: that the prophetic writings reveal and make known the mystery of Jesus Christ (Romans 16:25-26). We go to the Old Testament because it reveals and makes known our Lord Jesus....no other god.