This is an idle validation switch error.
Ecm sees one of the following:
Signal voltage from the throttle pedal is less than 0.6v for 0.25 secs while validation switch is not active.
OR
signal from throttle pedal is greater than 0.95v for 0.25 seconds while idle validation switch IS active.
If this happens, the ecu will debate and ignore throttle inputs.
Usually this is the idle switch failed, wiring is shorted, or switch is out of adjustment.