Put those spark plugs in on the weekend. For comparison:
I didn't notice at the time, but there's a heck of a lot less carbon on the old ones than there used to be. "Proof" that she's running better. It also looks like I need to change that valve cover gasket, if the oil on them is any indication.
Also did an oil change...
I went with 5w30 instead of 10w30. It seemed to make sense that since I do short trips (15km) that it would be beneficial to run an oil that is thinner, since the engine isn't fully warmed up for half of the trip.
Cold engine performance has been notably restored. I was assuming it was all about the spark plugs...but I had completely forgotten about the oil viscosity until this morning. Either or both are to thank for the perkiness of my engine when cold. (Or maybe it just likes the brand of gas I filled up with.)
Hopefully it makes a difference to my gas mileage.