Hey! I have some time on my hands and just thought I'd throw my two cents worth in on this topic, too, especially since you couldn't find an answer on FAIR's site. (IMO, you couldn't find a much better go-to site, although
Jeff Lindsay's site is a pretty close second.
Mormons believe that the individual known as Jesus Christ in the New Testament is the same individual as the individual known as Jehovah in the Old Testament. In other words, in
Exodus 3:14, which reads, "And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you," Jehovah was speaking. And in
John 8:58, when we read, "Jesus said unto them, Verily,verily, I say unto you, Before Abraham was, I am," the speaker is clearly Jesus Christ. So we believe that the pre-mortal Jesus was known as Jehovah to the people of the Old Testament, was born to Mary and became known as Jesus. There are literally dozens of verses in the Old Testament that speak of Jehovah saying or doing or being something that match up to almost the exact words in the New Testament which speak of Jesus Christ as saying or doing or being exactly those same things. I can list a bunch of them out for you if you'd like. Unfortunately, the information I have is in a book and not online, so I'll wait until I hear back from you before I start typing.