Is the throttle arm hitting anything on your intake? Try to run it by hand and see of you can get full throttle. Other than that possibly modifying the pedal to have more swing? Just some suggestions.
If you disconnect the linkage from the throttle body, can you get them to fully open? If not, why not?New cable still same result. Modified existing cable mounting point to move the linkage further. Now seeing above 85 percent had to drop one of the throttle return springs off to tight. Will update as the project continues