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Q: erratic timing light pulses on 1990 Ford Bronco

I have a 1979 Bronco with a 351 modified. It idles a little rough and bogs down on acceleration if I punch it too hard. The acceleration problem turns into a chug instead of a bog and pop after about 40 miles and gets worse. The engine has just been rebuilt and has a reman distributor. The plugs and wires are new as well as the coil and voltage regulator.The noise suppressor went bye bye with the old coil but I still have it When setting the timing I noticed the pulse missing and even firing at the wrong time every so often. This happens consistently on all wires and the # six wire fires three or five times each compression stroke. With the light on the coil wire and without blinking a dead spot can be seen. I know the light itself is good because the #6 spark plug is much cleaner and whiter than the others. Seems to be completely burning the fuel mixture. This is a duraspark system and the emissions label says this vehicle complies with California emissions. So I would think It is a duraspark I. Can anyone tell me why This one plug would fire multiple times and the others miss 8-10 percent of the time? Could this be caused by low compression on one cylinder?
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I bought this one from Autozone. I decided to replace the original because when i tore the engine down I noticed some lateral play on the old one.
I have an hei on the way from summit and hope my problem is the distributor. Its good to know a real tech thinks the same. I work on mack trucks.
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