Dr1rrrr

iTrader: (1)

So I just bought a 2013 Caprice with the 6.0 l77 after buying it I drove it 2hrs home without and issue. Then the very next day the engine started to make a ticking noise so I figured it was a dod lifter sticking. That weekend I removed the valve covers to see which lifter was collapsed and to my surprise I found none where loose. I then removed the spark plug to see what they looked like and cylinder number 7 was black but it looked fuel fouled not oil fouled. After removing the spark plugs I turned the engine over by hand to check that all the rockers moved and sure enough they all moved correctly. The next thing I did was a vacuum test and it held steady a 15in. After all this I was confused what I know for sure is I have a cylinder 7 misfire and a tick that sounds identical to the dod tick and low vacuum so what do you guys think?