I wanted to propose that "Let Go and Let G-D" is a pasuk in Tehilim:
השלך על השם יהבך והוא יכלכלך וגו' - תהילים נה, כג
"Cast to Hashem your burden and He will sustain you etc."

I found an article (in Hebrew) that substantiates this:
tora.us.fm/tnk1/ktuv/thlim/th-55-23.html

The author explains that יכלכלך can have a connotation of physical or emotional/spiritual sustenance.  He explains further that the function of the daily Amidah is all about casting your burdens on to Hashem, when we pray Ata Chonen, we cast off the worries of studying, when praying Refaeinu, we cast off our worries about our health and leave it in His hands, etc.

Disclaimer: I have not been through the 12 steps.

To me it sounds like it's saying that when you give up on your own ability to know right from wrong and what to do next, that's the best position to be in to accept Hashem's help.

Like Avraham Avinu when he said "who is the master of this creation?"

L' havdil, there is a video of Elon Musk watching his third SpaceX rocket launch. The first two rockets blew up, and there was no money for a fourth. He's a billionaire (now) and a genius, but in the video he says "any entities that are listening please bless this launch."

Notice how he deliberately phrases it in a way that does not describe anything he might have been taught about G-d, he leaves it wide open.

i think let go is based on the same idea as" there aint no atheist in a fox hole"