P0304 on LN2
 

I know the code is for a misfire on #4. I was hoping someone could set me straight on my troubleshooting. Here is what I've done so far, with no clear diagnosis of the real problem.

Coil Pack has no corrosion on plug wire contact.
No arcing visible during night check.
Pass-through spark tester shows spark.
Looks the same on #2 spark.
Plug is clean, not fouled.
Smell of gasoline on the plug, but not wet.
Cranked engine with plug out and resting on E Manifold.
Spark visible.
Sounded like good compression in cylinder.
Screwdriver test at injector and clicking sound is heard.
Did not do a Noid light test.
Opened Plenum and it is coated with residue inside!
Perhaps PCV or Exhaust recirc build up?
If related, why no effect on other cylinders?
Pulled #4 Injector
Fuel leaked out during removal. (Seems it’s getting fuel.)
Injector looks good, not dirty or gunked up.
11.9 to 12 ohms at connector.
O-Rings are not damaged, but upper one is a little loose on the injector body.

And that is where I'm at... Stumped. Any ideas?

Swap the injector with #2, see if the code follows it

I switched the plugs originally to see if I had a bad plug, to no avail. So I'll try an injector swap after I buy a bunch of plenum gaskets to give me access to the fuel rail. Plenum gaskets are cheap at O'Reilly, so I'll stock up on them. The assembly is certainly a pain to clean up after cracking it apart the first time. I'm going to vacuum out the ports before I crank the engine around to avoid sucking any crud into the valves or cylinders.

Thanks for your advice!