VW Jetta 1.8T 2001 low MPG?

I want to save my money.
My car is VW Jetta 2001 1.8T
I already changed my these stuff
1.Spark Plug
2. Air Filter
3. Engine Oil 5W-30
4. Oil Filter
And I also cleaned the Fuel Injection.
But the MPG of My Car is 20. I know the average is 25.
How can I save my gasoline in another way?
Any My Tire Pressure are correct

Your on the right track so far just make sure the correct air pressure is in your tires it is in the drivers side door and take anything out of your trunk that you dont need the added weight in the trunk will make your mileage go down