I'm pretty sure I responded to you in an email. It isn't so much were you connect to the existing harness. You basically need to make your own "new" connections. I found that the starter relay is a good place to get crank only and crank/run power supplies. There was a thread a while back that I posted a picture of a manual supplied by ford motor sports. It is EXTREMELY helpful with the EFI install. You will need a few wiring diagrams for the 91 injection harness.