1993 Ford Mustang 2.3L won't crank

I have a 1993 Mustang LX, 2.3L engine. My wife turned off the car, picked up my daughter, went back out to start the car and all we got was a "click, " then no power at all. Tried to jump the car, but nothing changed, just got the "click" and no power. Towed the car home. Unhook the positive battery cable, power comes back, then when the ignition key is turned, we get a "click" again, power goes away until we reset again by unhooking the positive battery cable and then re-attaching. Changed the starter/solenoid as well as the fender mounted solenoid, but we get the same thing. Not sure where to go from here.