Well, done all those things.
Changed injectors, we thought it was wiring problem. But tested and wiring is running fine.

It's weird stuffs indeed. When the car running (at least 2K rpm), all the cylinder works fine.
We did vacuum test (not sure if that's the right word/term) but only idling when misfire takes place.

We will have to check ECU after this.
It drives me crazy when problem is hard to identify.
All I am worried is that mechanical problem.
But my mechanic said, if it is mechanical then it should be misfiring even though not idling.

Any comments???