There are so many things that might be causing this; that I didn’t know how to reply to your question(s)? And what I do have to offer isn’t going to be of much help.
Find a tech that was at the top of his/her game when carburetors became computer controlled or at least someone that knows and felt very comfortable, working on carbs. Show a carburetor to a tech that is in their mid thirties; is like hanging garlic in front of Dracula; they’ll both run and hide.
I remember working on these systems and man what a can of worms they could be. Is it the carb itself, the electronics they bolted to and inside the carb, has the computer gone for a crap, is there an issue with one of the other emission devices, which they’ve bolted to the engine or pick none of the above?
A systematic step by step set of tests will need to be done; as to not condemn the wrong thing(s) that might be causing this.
Dan.
Canadian "EH"