in need of the detailed vacuum line diagram. Also any experience with capping not needed line and emissions i can remove for drive ability improvement. I know some guys are origanal all the way she is a driver not a trailer queen and will keep parts removed. Joe
My '78 (with '76 2.8) effectively had all of its long-broken emissions junk removed. AIR pump was frozen solid, catalytic converter was missing, EGR valve was leaking. I eventually replaced the converter with a modern 3-way non-AIR converter. The EGR can be tested to see if it's functional, otherwise replace or block off. Make sure the PCV valve is functional. Check all your vacuum hoses for leaking.
If your stuff is working fine, it shouldn't adversely affect driveability. But with it missing it didn't seem to hurt much either.
One suggestion would be to replace the carb with a 2100 or 2150 if you have the Variable Venturi carb. Another is to make sure your distributor vacuum advance is actually working and advancing the ignition.
I don't have the vacuum diagram unfortunately, sorry. I run about 3 lines - one to the distributor, one to the heater-core valve which also goes into the cabin heater controls, and a big one to the booster, all from manifold vacuum, and not counting the PCV which is intact. That's about it.
At idle my 2.8 pulls about 25inHg vacuum. If you're a great deal lower than that, your valves might be adjusted a bit too tight (which is tempting on our cars because of all of that lovely valvetrain clatter) or you may have a significant leak via booster, PCV, or other broken hoses.