I have had my car for like a month and it has been running fine then last night i started it up and it like reved itself a couple a times and then sputtered out. I started it again and its was still not idling right. I drove it home and it ran fine while driving but it wont idle right the rpms just keep acting sparatic and then the car shuts off. no check engine light. the engine is a 350 tpi. the car was originally a carborated 305. I'm not sure where to start looking for the problem. Help!