My 95 Mustang Build

This is my first car, 1995 Ford Mustang GT convertible. I bought it with some deer damage when I was 16, as I saved my money, I'd buy parts to fix it, I replaced the front bumper, drivers side fender, and hood. Last winter my wife and I pulled the engine and rebuilt it and stroked it out to 347. It was fun to drive all through the summer until one day after working the night shift, I came home and fell asleep on the couch. Only to be woken up by a phone call from the cops! My car started up by its self!(I leave it in gear and being a 95 is doesn't have a neutral safety switch installed) The car drove half a block taking out a street sign and then luckily getting stopped by the back of my truck! Thankfully no one was hurt, and that the guy across the street saw that IT STARTED UP BY ITSELF!!!!! otherwise I'm sure the cops wouldn't of believed me that it started up by its self! I wouldn't of! My project is now restoring it, and fixing the start by itself problem!