What do I think, you asked?
I think we are getting away from the subject of this thread "Cold start."
How about starting a new thread, call it "Mileage dropped," or "Low power," or "Sluggish acceleration," or whatever best describes this problem.
Clearly state the symptoms, and everything you have done or tried so far.
Thinking of those who may visit in the future, looking for info in a logical system.
Sorry, I have gotten pulled along in this as well, will try to do better in the future.