EPC light on check engine light on and air bag light on on 2002 Volkswagen Golf

when I start the car no EPC light but when I press down on the gas pedal the Epc light goes on and the car moves like a turtle and I already changed the brake switch Could it be the alternator or battery or does the gas pedal need to be replace??????? PLEASE HELP!!!!!!

Asked by for the 2002 Volkswagen Golf