The way I understand the backstory is Carter sent some of his people to try and bribe the Shah (in Paris if I remember correctly) to fire Brown and Root and hire his "people" at 10% more and the deal was his people would then hire B&R and make the 10% as a bonus... the Shah told them to pound sand and Carter let him be overthrown.
That's about it...
That is just unbelieveable, but Jimmy Carter was such a dolt anything is possible.
And that was the tip of it.
http://rescueattempt.tripod.com/id24.html
It all boils down to Iran
http://www.freerepublic.com/focus/f-news/1666626/posts