http://www.maverickcomet.com/defaul...Name=&dock=&Offset=240&LOC=/Repair/Repair.asp I see '75 and up vacuum diagrams, but not the '74 on this site. Maybe it wil help.
EGR Valve? wasn't blocked from the factory. Probably has a sticking valve or just been bypassed by a prior owner. If you don't need it for your local or state emissions, you can put the regular PCV spacer in it's place. Double check the spacer thickness to the stock (EGR spacer) spacer. Any appreciable difference will cause problems with your kick down rod.
Are you talking about the vacuum line with the screw in it? I doubt that would be plugged from the factory. Hunt through these and see what you can find: http://1bad6t.com/Maverick/repair/exploded_views_emission.html
That looks like it's on the "T" behind the egr valve. Probably just an extra port that wasn't needed after some of the smog crap was taken off. As long as it's plugged, it shouldn't cause a problem.
Alright I'll look into it. And thanks I'm in the process of rebuilding my engine an figured I find out before it goes back together
