Also check for vacuum leaks and leaks in the exhaust system from the manifold back if the above doesn't pinpoint your problem. There are a couple other things to look for, but for now it's probably best to start small and work to bigger.
John

 

Could very well be ignition timing or your vaccume advance not working properly. Valve timing could be a small part of it as well.

Ignition timing is not hard to fix. just look at the distributor, see that the rotor has proper play and snaps back like it should. Adjust it with a timing light. Should just be in the center of the manual adjustment if everything else is ok. For the valve timing, you need to replace your timing chain and other components. A timing set will give you the timing chain, chain guides, chain tensioner, two sprockets, and possibly a crank bearing. Set the new chain/upper sprocket at position #2 for better low end torque.