Hello my name is Dave.
It sounds like it's possibly a problem I have encountered in the past and that's the coolant sensor for the computer. You didn't mention if you have a MIL (check engine light) on, however I have seen quite a few GM products not turn the light on and still have a faulty sensor. If you have access to a scanner with live data I would recommend checking what the computer is being told the coolant temperature is by the sensor, if the temperature is reading considerably lower than would be expected at operating temperature (around 195 degrees) then that is the cause as it takes more fuel to run the lower the temperature. I hope this has been helpful and if there is anything else we can do to help we are always here and thank you for using 2CarPros.
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Monday, April 15th, 2019 AT 4:35 AM