Visual inspection under the hood did not identify a loose connection, darn it.
Additionally, I was incorrect in specifying that I had a bad valve. The issue was a bad ignition point, one of the spark plugs was not firing. Maddy's replaced the coil pack, ignition wire set, plugs and fuel filter. I think this was prior to the new alternator going in. That ran about $450 total.
I also have had one other major service event on the car I missed above not previously covered in other posts here. In December 2015 we had a very short, quite harsh cold snap that dropped temperatures rapidly from the 50s into the single digits and in the cold morning my radiator failed. I noticed it as soon as I returned from the drive and was able to drive it in to Carter and get it done in a day for about $500.