2000 S500 fuel injector or something else

Hello everybody
I got a problem with 2000 S500
Cylinder 4 and 5 has a misfire
OBD is saying that is a fuel injector circuit malfunction
I did check them by putting an electric light to a connector of fuel injector.
When I start a car they are blinking so they do have an electricity, but after 1 min of running engine, the power is gone. Only those 2 (4th and 5th) the other 6 cylinders fuel injectors working fine.

So, please, if anyone knows something about it, let me know :runaround:

Thank you

without getting into a complicated discription of the function of the engine control unit during a misfire,-- replace the plug wires.