Rattle on cold start, cyl 4 misfire

So plugs, coils, injectors and finally a new head gasket did not fix the cold start rattles.

Wiring is unlikely to be a problem since it runs fine after the cold start. There are continuity and ohm checks in the pdfs but a true intermittent electrical failure needs a 4 - 8 channel digital storage scope like a Picoscope and an experienced diagnostician.

Honestly everything points to a head gasket leak. A warped head, block or a loose head bolt has caused this sequence of events in the past.

 

From Wiring Diagrams for Injectors and Ignition Coils. All are directly driven by the ECM.



Picoscope Ignition Waveform (Typical)
Coil-on-plug (4-wire) - trigger and feedback - voltage.

 

Leak down test must not be an option