Is it normal for a v6 4runner to get 13mpg or less. I have a new engine all new fuel system and I have replaced all the sensors. I am running 32x11.5-15 tires on 10inch rims.

I would expect it to get better mileage than that on the highway, but if you drive in traffic much, that is probably pretty close to normal. That vehicle was not known for its mileage.

You are running larger than stock tires, that puts the engine out of it's power band, resulting in power loss and lower MPG.

It also throws you're speedo and odo off. If you didn't take that into account when calculating MPG, it's off too.