When a gas pedal is hard to press down, an issue with the throttle cable is the most common cause. This issue can be a kink in the cable or the cable not adjusted for the right amount of pressure.
Many drivers complain that the gas pedal is too hard to press at first and then slam to the floor. Other drivers may notice that no matter how it is pressed, the gas pedal does not respond properly. More than likely, this is a problem with the throttle cable. The cable is responsible for allowing enough pressure to get through the line to allow the pedal to be easier to press. If the pressure is too much, this can result in the gas pedal being hard to press. The first test to do is to visually look at the cables and see if a kink can be located. This can usually be straightened, but most people find that it can occur again over time.
If a kink is not present, then the car may have to be taken into the mechanic in order to test the pressure that is coming through the cable. If neither of these solutions solve the issue, check for any air filter issues that may be present, as they could be to blame.