I have a 51 Chevy Fleetline with a 235 and powerglide transmission. It ran fine during the fall, then it sat in december. I drove it last week and I had to leave the manual choke on a bit (it was like 30F outside) When I pushed the choke in, it would die. Even with the choke out a bit, the car ran a bit rough. Is this normal? Anything I can do? Should I rebuild the carb? This carb does not have the line that runs from the exhaust manifold to the carb.