(1996 ford crown victoria Lx) after turning ignition key to off position car will not shut off; must remove fuel injection fuse and disconnect battery for car to shut off.

It sounds like you need a new Ignition switch. There are a few tricks to changing them, but it is not too hard. You need to remove the plastic cover on the steering column. There is a hole below the Ignition switch that has a spring loaded pin which releases the tumbler.

You will need to disconnect the battery a few times to rotate the key through its Interlock features and be able to remove the Tumbler which can only be released in the RUN or ACC positions. You do not want the battery connected after the key is turned.

The plastic cover can get in the way and often the Tilt wheel may need to be moved to get clearance to remove the switch. Some switches have special heads on the screws which are called Security screws.

The switch is not too expensive and is available at most autoparts stores. You may also find tooling to remove the Security screws at an autoparts store too. The job should take no longer than 1 1/2 hours if even that long, more like 1 hour for most people.

This should solve your problem.