The injector wiring is rather limited in scope as there are four ECU pins each w/a wire running directly to the injector plug so if you wanted to replace this wiring then you are focused on just four wires. This does not include the four volatage wires. On a side note have you checked the two wires related to the secondary injectors at the ECU to see if either was pulled back in the ECU plug and thus perhaps not making good contact w/the ECU?

 

Have you tried some connection cleaner. I went through the whole harness on my 78 280z that was having issues. It made a world of difference. It might be worth a shot on your connections in question.

 

Just thought I would update. Finally had time to get back on this problem. Rotary eve nailed it...fuel injector clip wire. Resided new clip it runs like a scalded ape. Very happy and relieved.