straight six mad man

I've been having issues with my 1983 f150 4.9l 300. it's been running rough, Ive got it timed right and the carb is adjusted and Ive fixed all the vacuum leaks I can find, i discovered a cut hose at the top of the carb that has a bolt in it. I have no idea where it should hook up and I think that could be the issue. Any ideas where it should attach. the hose is red if that helps. And it's not on my diagram under the hood.