Actually there is a way to adjust the cable, Once the weather clears up, I'll post up pics of the parts I'm about to go over. Just behind the TBI unit, between the dizzy and the drivers side valve cover is a bracket where the TV cables and the throttles cables are attached. The TV cable has a plastic peice with a silver half moon on the side. This half moon is what allows the TV cable to be adjusted. Now it sounds to me like the cable is bound up, but if you press the half moon, you should be able to move the cable freely in and out. If not, the cable is bound up and you'll have to get another one. If the cable moves, adjust it so there is slight tension when the throttle is at the fully closed position.
You can also check the cable from the tranny side by removing it from the tranny. Front passenger side of the pan on top of the pan housing. Remove the one bolt that holds the cable in place and pull it from the housing. Using needlenose pliers, unhook the linkage, and use the pliers to keep the linkage from falling into the pan. If it falls, you're pulling the pan to fix it. From here, the cable should move freely, if not the cable is bound and the autoparts store is in your future.
Just remember if you purchase a new cable that if its shifting late on light throttle, the cable is too tight. If it's shifting too early, the cable is too loose.
