Alright guys, before i start i bought these plugs right after i got the truck from my dad and at the time i was reading other forums so that explains the bosch 2+, but now i got some TR-5s in there now. but when i pulled them there was some residue on the upper threads so i just need some advice as to whats happening.

Number 8 was the worst but i added some pics of the tips from random cylinders, the numbers can be found next to the plug

The first two are of #8

 

Valve cover gasket is probably leaking

 

ya thats what i was reading. i just wanted a opinion from the forums