It's clear to me that a pair of coils has failed in some way or has some intermittent breakdown. The coils feed cylinders 1&4 and 2&3 respectively. You need to test the primary and secondary windings on all 4 coils with a resistance meter, getting the same results for all 4 coils primary windings and then secondary windings, although the resistance of primary and secondary cannot be expected to be the same. Open circuit [hence no sparks] is shown by very high resistance in 100,000's of ohms. However an intermittent fault may easily pass such a test and the easiest way out is to go to a scrapyard looking for a car that was driven there, and get the complete coil and mounting assembly with the plug leads and plug boots, clean them all up and swap them for your own.
There is the slight possibility that the ECU box is faulty and they do go wrong sometimes without breaking down completely, but I doubt it in your case.
Lastly you could make sure the plug wires are neatly routed and not crossed with themselves or other wiring or cables, to eliminate the possibility of crossfire, although with only 4 cylinders this isn't probable.
I hope all your spark plug gaps are correct?