I can't help with the problem since you've covered most of the things I would know about. Last carb I worked on was my beloved VW Beetle, and I understand how things can run fine and then suddenly just stop for no reason. But in the end, there IS a reason, somewhere.
I just commented to point out if it helps, a carburetor is just a mechanical computer. It changes the input of fuel and air based on other variables. So somewhere in the code something is now not calculating the same as it was, or the variables themselves are different. I know that doesn't answer the problem, but it's something I've always been in awe about since being told my my dad that a automatic transmission is just a fluid computer. Which is funny, since he could tear down one of those, but never could "get" how an electronic computer worked.
Past few years it seems that I've heard good things about Hyundai's EVs, as opposed to the years of problems with their gas cars. I think I got the last generation that they build well, after was when the problems started hitting the fan.