Hello, I am new here and was hoping I could get some help. I have a 2011 Tahoe that has been idling rough. It also appears that my MPG is getting worse. I have tried changing the air filter and put the fuel additive in the tank but it did no good. I typically buy my gas from a exxon, shell or racetrac station and buy regular unleaded. I have tried a tank of premium but it didn't seem to make a difference. I know the logical answer is to bring it to a dealer but logistically that is hard to do and is my last resort. The vehicle has approximately 52,000 miles on it. Any hep or suggestions will be greatly appreciated. Thanks.

BTW, I am not very mechanically inclined.

Welcome to the forum Chris.
Has a tune up ever been performed on your Tahoe before?
When you say idling rough, does the rpm gauge show the rpm'* wandering a bit not steady?
If so cleaning the IAC intake air control, might help by removing it, and cleaning the pintle,spring area, with throttle body cleaner and re-install it.
Generally around those miles, I would want to have some new spark plugs in my rig and spark plug wires as well and install a new fuel filter.
The dealer would probably recommend an emission service as well, where they hook up special commercial cleaners to the fuel rail and let it run through system.
I use Techron Concentrate 2x bottles to a full tank and take it for a solid 2 hour + highway run at 70mph if possible.
Chevron Techron Concentrate Plus, 10 oz: Automotive : Walmart.com
Others have used Seafoam Motor treatment added to fuel with good success.
When do I add Sea Foam Motor Treatment to my fuel tank? - Sea Foam Sales Company
Hope this info helps.

I cannot answer the tune up questions as I bought the vehicle as certified used from a dealer a couple of years ago. I have a long list of things they did that qualified it as certified so I would hope that kind of stuff has been done. I am going to Florida next month so I can try the concentrate on that trip. Most of my driving is in town so two hours at 70 mph is not advisable. Thank you for your help.

If unknown, I would start by removing one spark plug, check the gap against specs, and view the overall condition. It may very well need new spark plugs etc as mentioned.

Ok, thanks.

Also did u ever get any MIL (check engine light)? If so have it scanned for codes.
Does the rpm wander not hold steady on rpm gauge? The IAC control the air mix and it is worth cleaning if so. Other areas to look at are cracked or broken, vacuum lines, & inspecting the PCV valve and checking the FPR fuel pressure regulator for not holding vacuum where fuel drips out of nipple, or is being ingested into line, while running 4 a while.
Just remove the vacuum hose from FPR and see if fuel drips out of the nipple while it running 4 a while, if it does... replace the FPR.

I never noticed the RPM needle jumping around. I think I may just bring it in to the dealership as I have no clue how to do that stuff you mentioned. I just hope it is covered under my extended warranty if there is something wrong with it. Thanks.

Isn't this covered under the 5yr/100K powertrain warranty?

sometimes they just run poorly in the winter if you live in an area where its cold. they put crap it doesnt like in the gas. i have never seen an oem plug or wire if its not melted not last 100k. being the engines are smoother you tend to notice it more. i notice it in my 07 more than any other car i have or had.

There isn't a idle control valve. Its all electronic with a sensor on the inside. Throttle body is probably coked up with dirt, pretty common. You will need to take it to the dealer and have this done due to the fact a idle relearn with a scanner after the clean will need to be done. Some of these did have a bulletin to replace the throttle body sensor due to a reduce engine power message and a ses light. And have them check for computer updates. Normally spark plugs don't need replaced until the 100k mark unless the are oil fouled, from burning oil. Some of the 5.3 engines with the active fuel management had bad issues with oil consumption.