So it gets better...
I drove around for about 2 hours today before noticing the same issue I had yesterday. First, the car isn't running as well as it did a few days ago. Just not pulling the same and it sounds a little funny. A/F looks good and I'm not seeing knock, but it just doesn't have the same get up and go. Well I was driving up a hill and went to pass a Camry. Hit the gas in 4th and as I hit 10psi, the car started to stumble again. i backed off and headed right on home. The car holds idle just fine, and when it's running, it seems to be running agreeably. Still, a little sluggish all-around, and acting like a punk when I put load on it.
One other thing happened of note... For the first time since I got a new dipstick about 6 months ago, the stick blew out and sprayed oil under my hood. Now I didn't come close to the 20PSI I was running just a few days ago fine before this problem cropped up. So now I'm wondering if I've lost compression in cyl. #3 (where the ugly plug came from) and now I'm getting blow-by and consequently, more pressure in the sump. I'm no expert in these things, so I don't know if blow-by could have also hosed the plug, but it seems possible.
Or maybe I have a bad injector and this one cylinder is running lean?
At this point I think I'm going to have the head pulled, check the pistons and sleeves, check the head gasket, and have the #3 plug threads repaired as they were pretty munched up by the last owner.
Oh, and once last observation. My walbro 255 was noisy as hell while idling in my driveway when I got home. I don't know if it's normally that noisy, or if I'm just hyper-sensitive to this stuff right now, but it seemed loud.