I have a 2001 Yukon that I’ve owned for 10 years… it’s going to sh!t. Replaced ECBM, radiator, deferential, window regulators, and the AC, on and on… It’s got 135K and the 5.3 is a piston slapping DOG. Serious lack of power and always has. I did a cold air intake free flowing exhaust.. Hypertech...