Well, I finally got time to tear into this thing a while back.
It just so happened that when I had the chance to start there was quite a bit of gas in the tank, so I decided to start on the other end.
I knew the coils, wires, spark plugs and the valve cover gasket were all possible suspects. So I started taking that apart first before going for parts. (There is a bit much to do just to get down in there for a simple check in my opinion, but it's not terrible)
Anyways I was relieved to not discover any oil down in there. The coils and wires looked ok, which doesn't always say a lot. The white plastic connectors had seen better days though. The input wiring to the coils will need repair/replacement before too long.
Anyways, I removed the plugs and new right away they needed replacement badly. They were not oily or anything. But they did have a good amount of white crust, the gap was rather LARGE, and the insulators were discolored from the heat exposure.
I quickly became concerned though when I started removing the second plug. THIS IS ONE APPLICATION WHERE... TRUST ME...
YOU !!!!MUST!!!! USE ANTI-SIEZE COMPOUND. They were not real tight or stuck. But I did feel they were going to strip out the threads if I was not EXTREMELY CAREFUL.
In fact, a couple of them required that I run them in and out a few times to actually get them to come out. SCARY.
After getting them all out, I sat down and thought a while. I had quite a self-debate about what plugs to put back in it. On one hand, I wanted to go with something extremely long life like one of the Bosch Platinum's... and on the other hand I wanted to play it safer thread-wise by going back with the exact same NGK's that were in it.
In the end, I decided to go with the NGK's thinking it might be safer on the threading. I put anti-sieze on them and installed. One of them didn't end up "feeling" real well at the end. But all seems to have buttoned up OK.
I'm still undecided rather or not I made the right plug decision. I mean it worked out... but the NGK's will likely have to be replaced again sooner. I don't know what I should do next time.
In the end though, this cleared my issues right up 100%.
Luckily it was just the plugs left that needed attention.