Would a crack in the manifold cause the AFM to not meter air and not let the secondary injectors come on? The car cannot rev past 4ks and it has a vacuum leak right on the front of it.

 

If you think about it, you would answer your own question. Isn't it pretty obvious that you need to fix obvious problems like vacuum leaks to go farther into any diagnosis with the fuel and intake systems? I am surprised that a question like this even needs to be asked! Fix the intake leaks and go from there.

 

Of course fix the leak.
Even a temporary fix will help you troubleshoot.

The secondary injectors are not used under light load, even at higher revs.
They are probably a symptom, not the problem.
If they are not comming on under load, it could be just a connector problem.

Switched plug wires can do that. It's easy to get them swapped when changing or checking plugs.
The front (leading) coils feed the bottom (leading) plugs.