< I only replaced the coil and post/boot related to cylinder 5.

>

Ok

Let me ask this, as i do not know what a" post boot" is.
Did you replace the plug connector under the coil that operates cyl 5 ?
Did you replace the plug wire going to #5 from the same coil?
Did you have the plug connector under the coil hooked uo when you tested for spark at 5 ?
You are aware that this is a series circuit that fires two plugs , in series?

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A Dalton