accelerator cable?

Woo hoo!!!! I seem to have a slight problem when I push on my gas pedal too hard, my 66 El Camino wants to go until it switches into the next gear.
I have gotten used to this problem be the ease of stepping on the gas pedal. My boyfriend however, won't drive her until I get the problem fixed, Hey, maybe a good reason to keep the preblem, but it is a little hairy sometimes.
I have a shift kit,and she is an automatic. How do I stop it from sticking? It can be dangerous. The cable isn't catching on anything. I've already checked that out. Could graphite help? Or would it just be a temporary fix?

ElCee Blue

has the cable been replaced before? maybe its too long than the original? or perhaps its the linkage on the carb