i have a 66 amlibu with a 3 peed auto and a 2 stage shift kit and to day it started runnin really ruff and totally revving out and sometimes i wont shift when my foot is on the gas i have to let it off. and i checked the vacume line and it is all good does anyone know what could be causing this

thanks

Sounds like it's slippin'... Do a search in the transmission section and I'm sure you'll find a ton of info.