94 Corolla rough idle when cold

Title says it all; it’s done it for the last few years, but this year it’s particularly bad. It only does it after a cold start and when the engine is coming up to operating temperature. Right as it gets to operating temp and the idle levels off to normal, it idles rough. After the engine thoroughly warms up, like if I drive it for a half hour or more, it idles OK. It just right when it first gets to operating temp and the idle rpms comes down to normal. The symptom isn’t present if ambient air temps are warm or hot, only when it’s about 40 degrees or less.

Coolant temp sensor? Air temp sensor? There are no codes, no check engine light, and otherwise, it runs great. All tune up items are new including the 02 sensor, plugs, wires, cap, rotor.

Thanks for any input.