Jeremy Salyers

Happy Holidays folks! Hope everyone's well and warm. I've got a 2013 Silverado 5.3L with 173k on the engine. I bought it at the beginning of the year with 150k on it and have been quite pleased with it till recently when the mpg went from an avg of 16 in town, down to 12. I had spark plugs replaced back in Sept, keep the oil and air filters clean, and the tires at proper psi. Can anyone help me determine what the culprit is for my recent loss in gas mileage? Thanks in advance