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hello my name is ***** ***** I will assist you. From what you are describing it looks like the carbs need to be rebuilt. To do this you would need to remove the carbs from the engine and open their bowls, then remove all the internal components and place the carbs inside carb cleaner for a couple of hours. Blow everything with compressed air and reassemble everything back. This should solve the problem but if you require further assistance let me know.
Sorry i did not get it was an EFI motor. If that is the case then most probably the problem you have is the temp sensor. When the engine warms up it will automatically adjust the air / fuel mixture but in your case it seems to be reading erratically.
I suggest you start by getting the temp sensor checked.