plug is firing pulled it has a white ish grey tip and 5 and 7 are not near eachother

 

ok so here is the update i checked the engine code again because the light goes on and off sometimes and now instead of just cylinder 7 misfire now im back to cylinder 7 and cylinder 8 misfire and multiple cylinder misfire codes. I also did a compression test and.... 1-140 2-150
3-140 4-135
5-145 6-70
7-140 8-75
so after i saw how low 6 and 8 were i put a little oil into those two cylinders and they came out as 6-80 and 8-85 so now what leak down test next i guess???