1997 Honda Accord accelerates slowly after shifting gears

1997 Honda Accord mileage: 106,000. Every gear I shift into the car takes an extra second before accelerating. I know how the car felt before, and when I shifted and hit the gas the car punched into gear right away. Now it hesitates and the rpm's rev up very slowly, after a while it eventually picks up speed. The only thing I did recently was change the air filter myself.