I'm guessing 13 MPG is not normal for a 2015 4Runner

As others have said. Check for dragging breaks, bearing noise, Change PCV valve, have the spark plugs been replaced? How did you confirm throttle body was cleaned? Air pressure, disconnect battery overnight and most importantly stop using no-name gas. Only tier 1.

 

If it makes you feel better, my rig gets 11-12mpg on average.

 

As others have said, that isn't the typical MPG. My 23 only has 10k on it, but I have a complete set of Talons garage aluminum skids (engine/transmission/transfer case) along with a steel RCI gas tank skid, steel RCI sliders, and steel SSO front bumper with a Warn Evo10 winch and still get 16 in town. Granted I drive like a grandpa, but even so.

 

I am in Ramona, Ca. And I drive up and down the 67 hwy. My 17 SR5 is lifted and I run 285/75/17 Toyo RT’s 34”s I average 15.2 mpg.
I forgot to add I use Costco premium fuel.

 

^ this here

I’ll add replace the air filter if you can’t positively confirm it’s been recently changed. Go with OEM.

Confirm Ethanol content of the fuel you are buying. E15 blend will drop your fuel economy a bit.

 

I pulled the air intake hose off of the throttle body and looked myself. I changed the PCV myself. The Carfax says that the spark plugs were done 42k ago, so that would likely help. I get no engine codes with my scanner. It coasts just as good as any other car and it does not pull to one side. So I doubt the brakes are the issue. They were done 9k ago at the Toyota dealer. I checked the air pressure myself with a digital gauge. Costco gas is "top tier" or tier 1. They sell 87 octane and 91 octane. My Tacoma takes the 87 and gets 19 MPG on the same roads. None the less, I'm going to try Chevron. We can't get E15 88 octane in California. King Gavin said that was against his will.