Lot's of variable there.. if you think it's not any of the sensors? But if any of the sensor is bad, it will throw you out of loop.
You said, it resolved after it warms up and only happened now... winter cold? Then, that can't be a wiring issue nor the value of the mapping on cold start, unless you change the value. I'm still leaning toward the coolant temp sensor. This sensor is the most important to the ecu during cold and hot start up. Coolant temp sensor will send signal to the Ecu, instruct the thermotime switch (cold start injector) to push more fuel less air (sort of choke in the old system). If the cold start injector or the coolant temp sensor are not functioning during cold start, the car runs rough....engine needs to get hot to reach the proper tolerance.
Check both....