Honestly, it sounds like it could be related to the coolant temp sensor. Basically, the sensor tells the computer the coolant's actual temperature. Based on that info, the computer determines what fuel/air ratio is needed. Here is denotative description of the sensor.
Engine coolant temperature sensor
The Engine Coolant Temperature (ECT) Sensor provides an input voltage to the ECM relating to coolant temperature. The ECM uses this input signal along with inputs from other sensors to determine injector pulse width and ignition timing. As coolant temperature varies the ECT Sensor's resistance changes. The change in resistance results in a different input voltage to the ECM. When the engine is cold, the ECM will operate in Open Loop cycle. It will demand slightly richer air/fuel mixtures and higher idle speeds until normal temperatures are reached.
Basically the same as what I said but with a lot of technical jargon. Lol With that in mind, if the computer thinks the temp is too cold, it will change injection timing and air fuel ratio. For example, if the coolant is 195 Degree F and the computer thinks it's -40 degrees F, it will make the mixture too rich (too much gas and not enough air) causing the engine to run poorly or stall. Considering that, it will also lead to other codes such as misfire (new plugs), O2 sensor faults and so on.
What to do.
The easiest way to check if that is the case is by using a live data scanner. With the scanner, one can actually see what the sensor is telling the computer and determine if it is correct or not.
Also, the sensor can be tested to see if it is good by checking checking resistance. Basically, you take the sensor, place it in a specified temperature liquid and check if it provides the correct resistance. (See pictures 1 and 2)
If I was there, I could check it for you in under five minutes, but. Also, if you have access to a live data scanner, check the sensor's readings when the problem is happening. When it is cold, the system runs in what is called a closed loop and the readings may be a false positive.
Based on everything you mentioned, I have a feeling this is causing the problem. However, I could be and have been wrong in the past. Lol But this is my first suspect.
Let me know if this helps. And by the way, I understand you would rather not have to be here for obvious reasons. LOL However, it's nice to hear from you again.
Take care and have a great Christmas.
Images (Click to enlarge)
Saturday, December 22nd, 2018 AT 11:51 AM