Key sticks after shutting off engine; column mounted ignition; key turns to shut off engine but gets stuck at 2:00 o'clock and won't return (or turn) to 10:00 o'clock for removal

sticking relay contacts in the PCM power relay , maybe . It's located in the central junction box . That is the inside the vehicle fuse box. That relay supply's power to the engine computer , ignition system , fuel etc.... If the contacts are stuck closed or sticking the engine would keep running with key off .

Poor ignition switch .Replace it and check for the blown fuses & your problem will disappear .As ignition controls the current to ECU so if the ignition will still be transmitting the voltage to ecu with the key turned off so how will a engine shutoff? think it's logical.You have been tricked by mechanic as it's not the computer fault at all.

turn your steering side to side into you can get the key, make sure is in neutral

Check the mechanical switch assembly that is on the steering column

There is a small cable attached to the shift lever that runs up to the ignition switch on the steering column. If it gets stuck, your shift lever won't move out of park and your key can get stuck and you won't be able to pull it out.

Drop the steering column down and detach the cable to free up your shifter and/or key. Make sure to replace it as soon as possible as it is a safety feature.

Look at transmission lock adjustment. the steering column is likely preventing the key from turning fully. Place well in park, and observe the column, and manually turn the column piece, for testing..

you can remove fuel pump fuse in junction box under hood to kill engine as for key if you look under the steering column near ignition switch you will see a little square plug remove plug and look in hole you will see a little plunger sticking out of a solenoid pull down on plunger and key will turn to off position either the lock solenoid is bad or you have a activation switch problem

Pull the 60amp fuse in the fuse box near the battery. You'll find it. That will shut off the motor. Remove the neg ground on the battery to shut off the rest of the car and save the battery,
It sounds like the ignition lock actuator. It goes from the ignition key switch to the Yellowish ignition switch box, under the dash on the column. It pushes the ignition switch to start and pulls it back to stop and lock. If you remove the 2 hex screws on the yellowish ignition switch and let it hang down, you will see a rod sticking out of the top. It's a slider. Push the slider toward the engine and it starts. Toward the drivers seat, and it shuts off the car. Check this out.
http://en.allexperts.com/q/Steering-Column-Repair-2047/2009/7/95-Thunderbird-1.htm

Hi,
This could be a tricky one - so just go through the options methodically untill you effect a repair.

If it has an immobiliser fitted - try using another key. Sometims the chip in the key fails.

If you did anything prior to this problem - jetwashing, using a mobile phone near the steering column, serious work etc - try these areas first.

Check alternator function.
Check fuses.
Check fuel level.
Look for leaks.
Check belts condition.

It is behaving like a major electrical fault. Check the BIG fuses in the engine bay fusebox. After this - check that the ignition switch is supplying a switched live feed when in the "on" position.
It could be a faulty switch contact. Possible if you have uprated lights somewhere.

Itsounds as though the rod that slides the positioner on your ignition switch has come loose or the swithch itself is loose and moving with the rod. To check this you've got to get to the ignition switch which is located at the bottom of the steering column. Take off the kneepad. Then you'll have to loosen and remove the two or three nuts mounting the column. This will allow you to get an eye on the switch. Check it for looseness. There are two slotted screw mounts for the switch. turn the key just a couple clicks(not over) and see if you can see the switch moving. I'm pretty well certain that your situation lies there. Thanks, Dana