Update: I tried starting it again today when I got home from work. Today it was warmer outside (71° right now, versus 48° on Sunday). It started on the first try, but misfired horribly for several minutes, then suddenly smoothed out.
I let it idle in my driveway as the engine warmed up. When the temperature gauge reached approximately 33%, the CHECK ENGINE light came on. The tachometer showed approximately 800 RPM, the oil pressure gauge showed approximately 60%, the battery gauge showed approximately 13 volts. I turned it off and did the “key dance” to retrieve the codes, and repeated this several times to make sure I got the codes correctly. The result is 12, 52, 55.
Based on my Internet research, code 52 is an internal fault in the PCM, is that correct? Time to look for a used PCM? 4-cylinder Caravans from this generation are rare, even in junkyards.
Here is one website that shows them “sold out”.