Spechtus

Hi guys!
My 89 Max SE's engine sometines goes rough - sounds like one of the cylinders is missing. I went to a mechanic to have an engine tune-up. He told that the problem is in one or several fuel injector "clips" (that's what he said) - fuel injector harness, as I'd been told in Nissan dealership. The part # is 24079-19P26. The 3pc kit costs $32, so for all 6 cyl. - $64. But they want $280 for install/replace. They told me the job is pain in the butt literally (so much for the courteous service, he-he). The mechanic told me that no body-shop would do the job - only Nissan. The engine works Ok after I just moved the wires - seems like the wire is broken inside or something.
If anyone knows the solution I'd be very grateful - don't wanna spend that much money on this. Or if anyone knows the shop in San Diego which would do the job for less money, please share
Thanks a lot.