Here is what appears to be your problem if I understand you correctly. I got this from another thread. It is tough to long distance trouble shoot...
The large Ford cap & rotor are the largest part of the upgrade.
By spreading terminals apart, you won't have as many crossfires (firing the wrong spark plug) and multi-fires (spark energy firing more than one plug at the same time).
The rotor for the larger/taller cap will lift up the spark energy out of the distributor housing, so you won't have the spark energy jumping to 'Ground' (the entire metal distributor body, and all the metal distributor parts are 'Ground') and instead, going to the spark plug terminals where it is intended to be and will do you some good.
Getting away from the factory cap, that is black, will help too.
To make those caps black, they use 'Carbon Black', a carbon soot product from burning fossil fuels.
Carbon is conductive, and will help the spark energy go places it shouldn't.
It's called 'Carbon Tracking', and once the cap has a 'Carbon Track' in it, it's ruined.
By using a true, premium dielectric (non-conductive) distributor cap with brass terminals, the spark energies will have a much better chance of reaching the intended spark plug at the correct time...
The vented distributor cap also vents out the build up of Ionized Air.
For a spark to jump, the voltage must ionize the air in the gap first, and since the spark energy has to ionize the air gaps between rotor and plug wire terminal on every cylinder, every time, there is often a build up of excess ionized air in the distributor cap.
That excess Ionized air allows the spark energy to jump anywhere there is an ion trail, which is anywhere and everywhere if the cap/distributor body if full of excess ionized air...
By venting the cap and the excess ionized air, ground fires, multi-fires and cross fires are substantially reduced!
This means for the first time since your vehicle rolled off the production line in '83, the spark energy is going to have a fighting chance of getting to the correct plug wire terminal at the correct time...
Now, if you use a good set of plug wires, it will get to the spark plug with out loosing a bunch of it's power...
The ignition coil (The E-core coil) is an easy way to bump up the USABLE spark energy a little bit!
Now that you have a cap, rotor and plug wires to deliver the spark energy, why not add some to the mix for cheap!
The E-core coil isn't a huge improvement, but will saturate much faster than the canister coil, and it can be mounted/run at any angle since it's not oil filled.
The E-core coil also has the advantage of working with about any factory style ignition module, and even breaker points if you use enough resistor...
Now that you have the vehicle starting and running much better, you may want to add a little more power...
That would be from adjusting the advance 'curve' (how fast and when the vacuum and centrifugal advance engage in relationship to the engine vacuum levels and RPM range).
By adding some advance at the right time you can gain some power in selected RPM ranges.
This would be from adjusting the spring pressures or weight of the weights for RPM changes,
And adjusting the mechanical limiters and/or spring pressure preload rates of the vacuum system.
All AMC/Motorcraft distributors have a spring preload pressure (vacuum advance rate) adjusters from the factory, so you lucked out there.
(If you would have switched to an HEI distributor, you would have to pay for a new vacuum advance to do this. HEI's are not adjustable from the factory)
A small file or Dremel tool will allow you to change the amount of advance.
Any more questions? __________________
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