Continuous Failure of Spark Plug in Cylinder06 - Leads to Misfire

Hello Everyone,
I have a misfire in Cylinder06 with CEL flashing and the code is P0306. My car is Tundra 2008 5.7 L with 186,xxx Miles
Here is the list of things already done:
1- Swapping the Coils (Misfire Stays in Cylinder 6)
2- Swapping the Injectors (Misfire Stays in Cylinder 6)
3- Compression Test, Cylinder 06 is 150 PSI (Wet Test)
4- Installing New Spark Plugs every time the spark plug fails after 20 miles of driving and the car starts misfire again.
5- No Signs of Oil or Coolant at the Spark Plug, The car has new valve cover gaskets + Spark Plugs seals
What could be the issue that damage the spark plugs, I'm testing the spark plug with the same coil used in cylinder 6 and the spark is blue and clean and Tested again after 20 miles driving the spark is yellow and misfiring !!
Now I'm on the process of checking the ECU and Wiring. what things shall I consider ?

 

Can you post a picture of the damaged plug?

 

You might consider looking at connectors in the wiring harness. There could be some green crusties hiding in the sockets and on the pins, considering the age of the truck and the miles.