Will using non-ethanol gas make my car run better?

Your car will run the same.

Your gas mileage will increase a bit.

The car's computer adjusts for different gasoline blends.

When the EPA  concludes any given cars estimated mileage, they use straight, no ethanol, gasoline.

A few years back I was getting 6mpg better on pure gas. I've noticed that something has changed either the formulation or the octane. Both are about the same now.

I use the pure due to the fact I have an older model and the ethanol is supposedly corrosive to certain plastic and rubber material. The 10% isn't too bad but the E85 requires a flex-fuel vehicle, which is made with corrosive-resistant material.

Heck, in my state we can't get non-ethanol gas. I live in the Nazi state of California.

Were you using E85 or E15? If E85 you should notice a little increase in mileage since ethanol has about 33% less energy than gasoline.

ethanol leaves a residue behind, that's why i never use it.

No it won't make any difference you could measure without some very sensitive equipment.