Ignition woes

Whoops, brain fart! 67Dart273 is right; you shouldn't leave the wire in place as I described, else risk constant starter engagement. Other-brand vehicles do use a wire from the starter solenoid to the coil for ballast bypass, but they do it by a dedicated terminal on the starter solenoid that's configured so as not to be able to operate the solenoid when it sees 12v on the wire connected to it.

If for whatever reason you're unable or uninterested to find and squash the bug in the J3 wire, you can effect a permanent workaround without starter backfeed by adding an ordinary 4-terminal relay under the hood, with its terminal #86 tapped into the starter relay's yellow trigger wire, terminal #85 grounded, terminal #30 connected to the large terminal on the starter relay, and terminal #87 connected to coil (+).