The Incommunicable Name was pronounced "Adonai," and where Adonai and Yhwh occur together the latter was pronounced "Elohim." After the destruction of the Second Temple there remained no trace of knowledge as to the pronunciation of the Name (see Jehovah). The commentators, however, agree as to its interpretation, that it denotes the eternal and everlasting existence of God, and that it is a composition of (meaning "a Being of the Past, the Present, and the Future"). The name Ehyeh () denotes His potency in the immediate future, and is part of Yhwh. The phrase "ehyeh-asher-ehyeh" (Ex. iii. 14) is interpreted by some authorities as "I will be because I will be," using the second part as a gloss and referring to God's promise, "Certainly I will be [ehyeh] with thee" (Ex. iii. 12). Other authorities claim that the whole phrase forms one name. The Targum Onḳelos leaves the phrase untranslated and is so quoted in the Talmud (B. B. 73a). The "I AM THAT I AM" of the Authorized Version is based on this view.
The Jews are extremely careful not to alter, erase or mistranslate a Name of God. This is why they often type "G_d" instead of "God" on the Internet - so that they don't accidentally erase a Name of God.
It is after all, a NAME OF GOD.
Breaking up the Name of God into individual phrases it looks like this:
Asher - could mean that, who, which, etc. depending on context.
Ehyeh - first-person singular imperfect form of hayah, to be which is usually translated "I will be."
If Exodus 3:12 were translated to English by that rule, it would look like this:
As a Proper NAME OF GOD it correctly translates and reduces to "I AM" in English:
God said to Moses, "I AM WHO I AM. This is what you are to say to the Israelites: 'I AM has sent me to you.' " - NIV
God said to Moses, 'I am he who is.' And he said, 'This is what you are to say to the Israelites, "I am has sent me to you." ' - New Jerusalem Bible
God said to Moses: I AM WHO AM. He said: Thus shalt thou say to the children of Israel: HE WHO IS, hath sent me to you. - Douay-Rheims
God said to Moshe, "Ehyeh Asher Ehyeh [I am/will be what I am/will be]," and added, "Here is what to say to the people of Isra'el: 'Ehyeh [I Am or I Will Be] has sent me to you.'" - Complete Jewish Bible
As soon then as he had said unto them, I am [he], they went backward, and fell to the ground. John 18:6
I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty. Revelation 1:8
Remember the former things of old: for I [am] God, and [there is] none else; [I am] God, and [there is] none like me, Declaring the end from the beginning, and from ancient times [the things] that are not [yet] done, saying, My counsel shall stand, and I will do all my pleasure: - Isaiah 46:9-10
To God be the glory, not man, never man.
Likewise, John 8:58 is not without its own problems and variants. Some manuscripts show the verse in the past tense (I was) rather than in present imperfect (I am being). To use only one of myriad examples, Jason BeDuhn and Robert M. Bowman (2004-2005) debated this at length, and BeDuhn writes the following (emphasis added; also text in [] is my interpolation):
Thus, we have translational and contextual issues here, which have been "harmonized" over the centuries. The fact that Onkelos Targums retain the Ehyeh-Asher-Ehye in the (Hebrew) original is irrelevant, as its pronunciation and substitution in reading varied over time and language (Hebrew, Aramaic, etc.), and the perceived meaning changed from one rabbi to another. Thus we have issues not only with the Ehyeh-Asher-Ehye but with John 8:58 and the much controversial ego eimi phrase.
In fact, ego eimi (which is a simply "I am") appears all over the New Testament and is never confused with the name of God. But in the Septuagint version of the Exodus 3:14 God is quoted as saying "ἐγώ εἰμι ὁ ὤν" (ego eimi ho on), that is I am the Being/Existence. It is the ho on that is missing in John 8:58, which is why there is reason to think something is not kosher with this verse. The ho on (Ο ΩΝ) is the equivalent of the Hebrew tetragrammaton (YHWH) which is why it appears on most icons of Jesus in his halo of later years.
But, as noted, the early church fathers did not make a connection between John 8:58 and Exodus 3:14. The ho on was missing in the former. So, no matter how you turn it around, what Jesus says in John 8:58 doe snot correspond to Hebrew Ehyeh-Asher-Ehyeh, not to the Septuagint version of Exodus 3:14.