car not starting when it starts it missfiring

I have a 1999 Ford mustang v6 and just recently iv been having issues with it the problems all started when I could not start it come to find out it was something to do with the anti theft so now I have to watch the theft light to be home or not blinking to start does anyone know why? my second question. car started one morning while driving my car stalls I start it back up but now the rpms are jumping and back fires engine codes say camshaft position sensor and two others cant remember but i replaced it ran ok but started again same issue but car feeling like it's not running on all cylinders??