I have an 83 t-bird swapped the 3.8 auto for a 302 auto,starter stays engaged.

I repalced the 6 with a 302 auto,the starter wanted to stay going even after the key was off.I replaced the lock cyl and ignition switch nothing changed so I replaced the solenoid tore the dash apart looked at all the wires and fuse panel nothing, replaced the starter even put an in line100amp kill switch between the solenoid and the only wire to the starter still does it.I tried both points on the noid also".HELP" out of ideas