What could explain a truck that starts on its own?

My 95 chevy s-10 starts on its own in the middle of the night and I don't believe in ghosts.  I now have to disconnect the battery every night. I have to be careful when removing my key or it will start in the acc position when I turn it too far. Put in a new ignition and I still have the same problem. Somehow something is loose and slips into the acc position....it can take 5 minutes or hours if I don't disconnect the battery.  I have tried to visually find a short in the wires running through the column but no luck and am worried about testing live because of air bag wires. With no key in the ignition I can slam a door or lift the tilt wheel or slam the hood and it will try to start.  I put in a new ignition and I still have the same problems.  Now my key doesn't stick any more.