I have a 97 mustang GT 4.6L with an automatic trans. The car developed a starting issue where it would start sometimes and other times it would'nt. Then it just stopped all together. If i wanted to start it i would jack up the car turn on the ignition crawl under the car and start it. So i replaced the nuetral safety switch or trans range sensor thinking that was the problem but was not. Now i'm thinking it is the ignition switch or the theft deterrent system but not sure how to find out as im about to pull my hair out on this one. Any suggestions?

 

Sure it's not just something as simple as a starter solenoid? I would start with the basics before you drive yourself nuts with theft systems. Make sure you are getting signal at the trigger wire for the starter solenoid and if you are look into the starter/starter solenoid.