Mine started doing it with the lift and bigger tires. I've had to change my shift points. I use to shift to sixth around 50. I noticed a lot of pre ignition after the tires and lift. Now I shift latter around 60 into sixth. Guess regearing will get it back to where I think it should be.
2013 JKUR-Fiat. Rock Krawler 3.5 X-Factor, RK Draglink flip, Nitto Trail Grappler 35x12.5x17, ACE Rock Sliders, Poison Spyder Brawler MID Front Bumper with Brawler Bar, ENGO E10000S Electric Winch, ACE Engineering JK Pro Series Rear Bumper with Tire Carrier, JW Speaker 8700, Dually Fog lights and sPOD