My throttle used to stick when I went wide open. Then I noticed the TV cable was loose. There's supposed to be a grommet to fit the hole in the linkage and the TV cable. The ones I found did not fit from RockAuto. My mechanic used a custom setup with an Eclip when the transmission was overhauled.
I used bailing wire as a short term fix between my discovery and the tranny overhaul.
I read here an experienced transmission shop will be able to get the parts you need. That may be cheaper than what I tried.
1992 Tbird LX 5.0, 3.73 gears, 1995 Cobra intake, deleted air silencer, 2.5" mandrel bent dual exhaust, SCP shorty headers. Updated four-hole fuel injectors. SK shift kit in AOD. Vogtland 0.9" springs, Tokico and Bilstein shocks.