ncg:

The first diagnosis steps will be to examine all the ignition system components for condition: distributor cap & rotor, wires, spark plugs, and the ignition controller (EZL) for clean and secure plug connections.

Second steps are to do both cylinder leakdown, and compression tests, first with the engine cold, and again with the engine warmed up, looking for any significant difference between cold and warm.

After both cylinder condition, and the ignition system are deemed good, then attention may be directed to the fuel system.