What are the codes exactly, P0303 and P0305 ? No more ?
The coil packs failing is just one of many possible causes of a misfire. There are loads of other possibilities. The coils are obviously fine if you've changed them all and are still getting the same problems.
How about the spark plugs, are they ok ? Have they been changed ? The injectors could be faulty, could be valve problems, lack of compression in those cylinders due to damage, electrical problems, fuel issues, etc, etc.
When did the problem start happening, had some work been done on the car shortly before then ?