What's wrong with the throttle speed 1200 of large trucks?

1. Throttle cable problem: There may be burrs or wear inside the throttle cable, resulting in poor throttle return. Need to check and replace the throttle cable.

2. Throttle and idle motor problems: Throttle and idle motor may return badly due to carbon deposition or dirt. Need to clean or replace the throttle and idle motor.

3. accelerator pedal problem: the spring in the accelerator pedal may be broken or damaged, resulting in poor accelerator return. Need to check and replace the accelerator pedal.