If you ever held the "drive by wire" gas pedal assembly in your hand and I have just today at Mitsubishi, it is very possible that the spring loaded piston can stick.
The original styles look like the bottom assembly in this picture. Basically a spring loaded rod with a sensor that measure rod movement that sends a signal to the EFI control module.
The one I examined today at Mitsu has a spring attached to the end of the rod and the spring rides on a nylon piston. This nylon piston slides in a stamped steel cylinder. A similar sensor measures rod stroke. It's quite possible the some contamination, sand, dirt, etc. could enter the stamped steel bore and impede or jam the spring's stroke.
My point is this Toyota issue is quite possibly mechanical and not a function of an ECU/EFI system fault.
