Auto trans. Help please!

[Peter Mc Mahon]

Hi guys, I could use with some help. What I have, 56' F100 with 11' coyote crate motor and 2000 ish 4R70W trans with stock convertor and a pcs simple shift transmission ecu. The problem, I built everything and today was first time ever putting it in gear. When I put it in drive or any other gear it wants to go. I need to stand on the brakes heavy to keep it stopped. I don't have any error codes on my simple shift and all base parameters are set correctly. I am guessing that my convertor is not 'slipping?' Any ideas? Thanks