Need help: engine turns off on it's own

Sorry for not saying it before, the car wasn't lucky to get power brakes. I checked the carb this weekend, I notice it was missing a nut where the carb goes on the manifold. I put one on and tighted up the rest of since it they were all lose. Before I took the car in, it wasn't like that. I know that cause a buddy was showing me how a electric choke works. He adjusted the some likages that were comming lose. I'll check the mainfold if its lose to night. As for the carb, I opened it up it looked pretty clean. I would have my friend check it but he moved to another state.