Changed the plugs last night and can make a few interesting observations. First off, without knowing what kind of plugs were in it as I can't recall from the last service, I put in Bosh FR6KPP33X+. The old ones were also FR6KPP33X+. They haven't given me any trouble since the last few days, so I can say this - the Bosch FR6KPP33X+ plugs were great, but up to a point. They were only about 24k old when I started to get the misfires. I suppose getting the original pfr6t-10g ngk plugs would have gotten me a bit more longevity, but at double the cost - water under the bridge.
I also noticed what looks to be a possible head gasket leak? Please look at the pics and give me your opinions - preferably from members who have seen this on their cars and had it repaired. No water in the oil, and no oil in the water, but cyl #1 has some rust on the seat of the plug, while cyl #2 has some oil on the threads. Three and four are pretty as can be. The old plugs were all looking good although they seem to be part of the misfire scenario that I was experiencing. After putting in new plugs, adding some STP injector cleaner and filling with 91 octane, the misfire seems to be gone. I'm sure I'll pass smog, but the small amount of rust and oil still needs to be addressed.
This is basically what bore three and four look like.
This is bore two. Bore one looks similar but oily, not dry. Forgot to take pic of two.
Plug from bore two. This is very likely the reason my coolant gets low so often.
Plug from bore one. I'm also concerned about the nick on the ground electrode. I'll take another pic of all plugs lined up side by side for comparison. Three of four plugs have a blemish in that same area of the grounding electrode. Plug one is just the worst.