Won't Start need advice, Please read....

I am perplexed to say the least. My Dodge Dart when I took it out this spring was missing and bucking and wouldn’t stay running. I am figured it might be the carb so I bought a rebuilt carb and thought that would solve my problem. I couldn’t be more incorrect. This is what I have done so far before even attempting to start the car I replaced the fuel filter. The car tries to start and I can smell exhaust but if it does start it is only for a second or two. I took off the fuel line and turned over the engine and the carb is receiving gas as I saw the stream of fuel, even pouring fresh gas down the carb the car still won’t remaining running. My next thought was spark I took off the spark plug farthest away from the distributor and it was getting spark. Does anyone have any ideas? Could the timing chain have jumped? It is a rebuilt engine 3 years ago and probably has 200 miles on it since the rebuild. Other than what I have mentioned I have no idea and would hope someone could point me in the right direction….

Thanks for reading and commenting.