misfire

I bought a 2005 STS a few weeks ago. I knew it needed help, call it a rescue(well maybe). First thing I did, after checking fluids of course, was change out the spark plugs. When I did that, I found oil in a couple of the wells, so I swapped out the valve cover gaskets. No more oil in the wells...

Bit of a weird week. I've a 2008 CTS4 DI that earlier this week the check engine light blinked 3 times and then went out (indicating a misfire as I understand). Ran it for a day planning on doing spark plugs over the weekend. Before I could though, it threw a p430 so I figured I probably blew...