Assuming the linkage between the accelerator pedal and the engine is unobstructed (something you can check visually by checking around the accelerator pedal or floor mat for foreign objects that may be obstructing the path of the accelerator pedal), a sticky accelerator pedal is almost always due to accumulation of unwanted dirt at the throttle body. This makes the action of opening and closing the throttle a notchy, imprecise operation.
Common reasons for this to happen:
- Throttle body is stuck
- Accelerator pedal sensor malfunction
- Accelerator cable broken
- Accelerator pedal return spring broken