I have 84 camaro h.o. and i just installed a edelbrock performer series intake with a 600cfm holley and now the car wont hardly run and is weak as water where did i go wrong ? is it a vac problem?

Are you getting spark? You've put a 2001 engine into a 1986 body. The 2001 engine ran with an engine control module (ECM), the 1986 doesn't have that. The 1986 probably has an electronic ignition module that works with the 1986 coil and 1986 reluctor/distributor. You may want to compare the two distributors and the two coils.

Yes.
The spacer could be leaking inside - the spacer should match the gasket for the base of the carb and the intake.

It is the primary ports for the smaller throttle valves of the staggered bore carburetor like a Delco Quadrajet or Holley spread bore.

Yes the existing manifold will work. 750 is WAY over carbureting the engine you have here.

In all my experience, if you know how to correctly tune a edelbrock then go with that, but, holley has outstanding carbs that can muster up to an output of 1,200hp. it would be much cheaper to et a rebuild kit from say, o'reillys, 20-45 dollars depending on which one you have.
I have a 1985 Bronco 351w 4x4, i just rebuilt my holley and she runs smooth

You need a matching manifold or an adapter. Most any auto parts house will have one.

If your staying with the stock intake manifold the edelbrock wont fit unless you install a adapter plate.And i would advise you not to install it will not seal properly.I would install a edelbrock intake manifold and carburetor as a matched set.You can purchase a edelbrock carburetor and intake manifold from advance auto parts that's designed for your vehicle.

it would be easier to buy the adapter but holley al;so makes intake manifold for this problem they are pricey but you get the full 600cfms with an adapter you wont get as much oomph out of it but and adapter is a good idea especially when you dont have 300 to blow on the manifold

You may want to install an adjustable pressure regulator to provide what the engine needs, not what the computer thinks it wants...Check with Holley, Moroso and Edelbrock to see if they have something that will help. Of course check the management controls to make sure they are working, but except for the MAP, I would expect a lean not rich condition from those items. If you are using one, check the mass air flow sensor when dirty inside they can cause problems.
Good luck (always said someone should build a 440 mag "69 charger with electronic injection...want to see quick???