My 91 TOYOTA Corolla (2E engine - carbureted) idles rough when cold. I have to step on the accelerator pedal to support and lessen the engine's rough idling. After warming up, it idles smooth. What seems to be the problem? Are there any adjustments I can do? Carburetor overhauled with new distributor cap and wires, new fuel filter, new air filter, oil changed and ignition timing set as specified.