1993 taurus GL wagon electrical problem, no start

My 1993 3.0 wagon will not start. Here's the symptom: voltage across the battery is 12.5 volts with the key off. Turn the key in the run position and voltage drops to 11.9V. Turn the key to the start position and voltage drops to about 6 volts. Return the key to the run position and voltage slowly climbs up to about 9 volts and stabilizes. The starter never turns and the dashboard lights flicker. Removing the main connector at the voltage regulator at this moment raises voltage to 10V, replacing the connector drops it to 9V again. Turn the ignition off, battery voltage rises to 12.5 volts. Immediately turn it back on and again it drops to only 9 volts across the battery. Turn it off, voltage goes to 12.5V, and wait 60 seconds and turn it back on and there is 11.9 volts across the battery again and you can repeat the cycle. This will occur with all of the underhood maxi-fuses pulled except the #1 and #2 60A fuses, the battery wire and the solenoid wire diconnected from the starter, and all interior fuse box fuses removed. Please help I'm baffled.