first, make sure that thing hasnt been touched by toyota before.
(har-har) /retard.
but, just trace the cable, make sure theres nothing snagging it.
make sure its adjusted correctly.
with the car off, open and shit the throttle body to see if its sticking. may just need to clean it real good.
if all of that is correct. check that the spring to lift the pedal is still attached. may have popped off or broken.