2001 Ford Mustang GT manual, won’t start, but anti theft light flashes. I was driving the car and it just died, wouldn’t start back up.
No CEL light?
Google that symptom, there are more than a few replies. One was, disconnect the battery for 5 minutes, reconnect, turn the key to the ON position but don’t start it, leave it on for 10 minutes and the car will start. Can’t hurt to try it.
Another post indicated a ground wire up on the radiator core support gets corroded and sets the anti-theft. Bad grounds are always a possibility. Clean any and all grounds you find on a car this old.