Technical Diagnosing a p0304 error

[scaphoid]

I have a 2011 Fiat 500 1.2, 69 Hp.
The other day the engine lamp turn on and the car began to miss fire. I diagnosed it with an OBD and it read fault nr.P0300 and P0304
I have tried to change the
- sparkplugs
- sparkplug wires
- coil bridge
- pressure tested the cylinder witch was ok
- Resitting the ECU
Still, the same fault comes up. So my question is, what's left? except a faulty ECU, can it be anything else ?

 

[A3jeroen]

Injectors?
Coil bridge is coil? The 1,4 has 4 pencil coils and by swapping them the fault shifts with the swap. That made it easy to diagnose.

gr J

 

[scaphoid]

I don't know if I can swap the coils when it's a coil bridge, and regarding the injectors, should there not be a default code if that was the case?
Greetings K