Update! Finally!

While I was running my fuel pressure tests a couple weeks ago, I started wiggling various wires on the engine. When I wiggled the wiring close to the connector on the MAF sensor, the engine started running rough and surging until it finally died. Then when I started it back up, it ran okay and hasn't acted up since. The connector was tight in the MAF sensor, but I'm thinking one of the inside it was intermittently losing contact.

I bought some electrical contact cleaner from NAPA, and some grease for electrical contacts and applied both. We'll see now if this issue is resolved and I will report back.