How many miles on your truck? What weight oil you running? How often do you change it? Sounds like a cam phaser failing, take it to the Stealership. Common issue on the modular engines because they are oil pressure actuated and any crud in the journals will cause them to stick in the default position due to lack of flow and pressure.
EDIT: IF it were a tune issue it would have happened immediately after you uploaded the calibration.
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