#3 and #4 spark plugs share the same coil in the coil pack, they are wired in series

So if the one coil was bad I would expect #4 to be effected as well

V6 coil pack has 3 coils inside, each coil sparks a "matched set" of cylinders
Multi-cylinder Engines must be balanced, and those are the Matched sets or Pairs
For 4 cyl engines usually 1 and 4 are at TDC at the same time, and 2 and 3 are at TDC 180deg later.

The 3.0l V6 uses 1 and 5, 2 and 6, 3 and 4, each pair is at TDC 120deg apart
And that is why the coil pack wiring is the way it is.
3 4
2 6
1 5
front

Or
1 5
2 6
3 4
front

1 and 5 are on the same coil, as are 2 and 6, and 3 and 4

It is called a Waste spark system, actually the very very first spark system ever used on the very very first gasoline engine.
It sparks at every TDC, not just Compression stroke TDC.

Since 3 and 4 are both at TDC at the same time, one will be on compression stroke, the other on exhaust stroke, both spark plugs spark, so the spark in the cylinder on its exhaust stroke is "Wasted", since it doesn't do anything, no it doesn't "clean exhaust better, lol.
It's just easier to setup this type of spark system timed from the crank.

Now a weak spark could cause misfire in just one cylinder in this type of system
But you can test for that by swapping spark plug wires at the coil pack.
Reverse 3 and 4
If misfire moves to #4 then replace coil pack