99 elantra no spark?

    My girlfriends 99 elantra has no spark I have a haynes manual and am guessing it is 1. the crank position sensor 2. crank angle sensor 3. cdi box 4. ignition coil or 5. hopefully not the ECU. She drove it to work went to drive it home and it wouldnt start it had been running rough and stalling in weeks past but recently had been running fine I am just wondering if anyone has any advice on which of these I should replace first.  any response would be greatly appreciated.

My guess would be the crankshaft position sensor.  That's what I'd check first.