yeah, I had a 04 Suburban then I was able to get back into a truck with an 08 Silverado 4x2 crew cab. both had plastic dash issues, and the 08 did suffer the AFM failure at 185k (bought it at 175k). got lucky and only had to knock the lifter loose instead of replacing the whole system, but immediately Disabled the AFM system before even starting it back up. as near as I can tell, didn't really affect fuel mileage and when it did primarily in stop/go driving