So, the black beast was getting worse gas mileage, and backfiring/missing/hesitating/coughing (insert adjective of your choice) below about 1500 RPM's.

The ONLY cure was a bottle of Techron in each tank of gas. This was with using Top Tier Premium gas.

Well, I finally had some time to wrench on it, and spent New Years afternoon replacing the spark plugs.

Well, so far, that has fixed the issue! No more (insert adjective here)!!

Gave the old ones a thorough visual inspection, and didn't see anything out of the ordinary. Deposits and color were good. The only thing that might be out of spec is that the center electrode was inset into the ceramic a couple thousands more than the new ones. As far as I know, 101K miles on the plugs..

So, all is good again!