It's a little difficult to diagnose remotely. Are you sure that's 5.8 km/l? Thats's 17l/100 km which is more than hard driven GT-P!
To answer your other questions:
There is no
MAF on the carb engine.
Check the ignition timing, points and
distributor cap for wear.
I've got a WSM at home so will check over the weekend for an image of the vac lines.
Cheers
Russ