here is a FREE recall on Ford ignition switches. They overheat and sometimes catch fire.
Copy down you VIN number and call the Ford dealer nearest you. Tell them you want to see if the ignition switch recall for Fords & Mustangs was done on your car. They will ask for the VIN number & check it against the master database. If it isn't in the database, then you can schedule an appointment to have the switch replaced for free. The TSB is #95S28, and don't let them tell you that they don't do that anymore. They will not give the part so that you can install it. The rules of the recall are that they must install the switch to prevent any legal problems.
If the Ford peope won't do the free recall, the switch is $13-$15 at most auto parts stores and takes about 30 minutes to change. The main thing to watch out for is the plastic connector shells for the switch wiring harness can have some heat damage. That makes a simple swap job a little more complicated because the wires fall out of the connector shell. Any connector shell that won't hold the connectors in place should be replaced. That means a trip to the junkyard and some sweaty work among the skeletons of dead horses...
You may need a Torx screwdriver for some of the screws, but the auto parts stores will have them too. The usually charge less than $5 for the screwdriver.
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.
You will need not just torx bits, but theft-deterring torx bits (there is a difference) to remove and install the 2 screws that mount the ignition switch.