crankshaft or camshaft position sensors
another thing that can happen unexpectedly and there are no warnings or means to detect it, is a crankshaft or camshaft sensor failing. and the symptoms are erratic, to make thing even worse.
what i have heard suggesting is just to replace both now and keep the spares in the car in case any fails again. this way at least you have them handy and just need to replace them in case of failure.
removal of the camshaft sensor is easy and is at the reach of the hand at the front, but the other is not, so here is the routine:
Replace the Crankshaft Position Sensor on a Chrysler Crossfire
and also make sure that you get bosch brand.