This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
George Young suggests:
1) Not enough voltage from old damp coil? - new coil.
2) EGR valve plunger binding open?
- remove and plug manifold vacuum hose to EGR circuit.
Dave adds: Better wires, high quality rotor/distributor cap for
best fit. Check the stove, that big metal thing on many engines that feeds
warm air from the engine to the air intake through a usually-rotten or missing
hose. The vacuum-operated flap may also not be functioning for one reason or
another, usually a bad vacuum hose. This is common. Dan Stern notes the flap is
controlled by the Thermostatic Air Cleaner vacuum motor...
George Young adds: My old 318 ran rough when cold and
wet, would stall out until warm. Choke was the problem. Manifold
carboned up and wouldn't pass heat to choke coil thermostat. Changed to
manual choke and no more problem and increased gas mileage
Dan Stern noted that driveability problems could be caused by a bad choke
control unit, which may short out and shunt full power to the electric choke,
causing it to heat up prematurely.