Hi, my fifth ave has not been able to stay running in this cold weather. It will crank and start up but if I don't keep revving it, it will die. When I am revving it however, it idles very rough. This started after a very cold night where I only had a quarter of a tank. I thought that the fuel filter might have froze so I replaced that, but still no luck. Is there anything else I should try?
If it only stalls when the engine is still cold, suspect the automatic choke is out of adjustment or the linkage is disconnected. If it acts worse after the engine is warmed up and you see black smoke from the exhaust, check for a plugged exhaust passage that goes through the intake manifold under the carburetor. It's purpose is to heat the thermostatic choke spring and warm the base of the carburetor. Two problems can occur. That passage can get plugged with carbon, and the heat-riser valve on the right exhaust manifold can get rusted tight. It is supposed to close that manifold when it is cold so all the exhaust from the right side of the engine has to go through that passage and out the left side exhaust. The Chrysler dealer's parts department has a REAL good rust penetrant called, ... Uhm, ... Well, Rust Penetrant, designed specifically for that heat-riser valve.
Problems related to that valve or the passage have a bigger affect on engine performance when the engine is warmed up. There is also an electric heater on the choke spring so the choke will open eventually.
The problem could also be nothing more than a tune-up is needed. A bad spark plug or wire will make the engine idle rough and too slowly.