So i just bought this cobra. Tonight i take my uncle for a ride down the interstate. i get it up to about 100mph then let out...when i pulled the car into neutral it jus died on me and turned off. I got it stared back up. Then i get to a stop light and it dies again. so we roll start it and it runs fine until the rpms drop.. I believe my alternator is shot....do you guys think thats what it could be?