PS, here is an extensive article on the subject. Hope it helps. http://www.christian-thinktank.com/trin02.html
Andthis is how it ends, a bit of a summary.
"What emerges from this cursory study of some OT passages is a concept of a plurality of agents, that are very much God, but still somehow separate agents WITHIN God. So the Angel of YHWH seems to be the main 'external interface' with humans and the Spirit of God seems to be the main 'internal interface' with us. In other words, an Israelite would meet God 'face-to-face' in the Angel, but would be confronted with God INSIDE his thoughts by the Spirit of God.
Conclusion:
There seems to be an abundance of 'stubborn' data that there are multiple agents who can be appropriately called 'YHWH', and although there are STRONG prohibitions against idolatry in the OT, NOT ONCE is there any indication in the text that ascribing deity to the Angel of YHWH or Spirit of YHWH is considered blasphemous. Indeed, the grammatical and lexical data gives reasonable indication that plurality may be a basic aspect of the One God of Israel."