I have recently purchased a 2010 Silverado with a 5.3 with 35xxx miles. When I test drove the vehicle it drove great. Now that I have had it a few weeks I have noticed it seems to make different sounds mainly I think when the active fuel management starts working. I am not getting that good of gas mileage, I was hoping for 18-19, I am however getting 16-17. the truck is bone stock. I have been trying to drive half way decent to see what the highest mileage is I could get. I have started to notice that when you are coming off of cruising thottle to accelerate it makes different noises almost like a skip. i know it isnt skipping, otherwise it would log a dtc. My question is, Why kind of mileage is everyone else getting? i never see a light or indicator when the afm is working. Is this normal on this model ? I have read alot of posts where people wanted the afm removed simply because of the different sounds or feeling when it works. i dont mind so much, i would care less if I were getting better mileage. Just a little about myself, I am a master tech we lost our gm badge right after obama made gm obama motors. (we were one of the medium dealers that got a pink slip). I do however currently have a tech2 in the truck, we dont have access to tsb's now. But, I have all kinds of toys to play with. . i have been working on gm's for over 10 years mainly medium duty, aka duramax etc. . I can help myself, and have no major complaints with the truck. Since I am a tech by trade and am not familar with the system it's driving me insane when it works and there is no indicator. Just looking to see how the system works for everyone else. Any and all input would be greatly appreciated.