I'll bet you were low on trans fluid.. Lets see what they say.
The battery is dying. Transfluid is fine unless someone touched it.
Tru DatThe fact that a battery "holds a charge just fine" doesn't mean you're good. I admit that this is just a theory of mine, but your CPU depends on a STABLE current in order to function correctly. This includes getting good info from the sensors as well as the power supply to the CPU itself. The battery acts as a power sink and defacto surge protector, absorbing voltage spikes and smoothing the current. Once the cells start to deteriorate, they no longer can perform that function, even if they still can hold plenty of current to perform the more traditional job of cranking the starter.