Need Help with Tune up

[jsa2000]

I changed the spark plugs on my 1993 Q45. The engine is still riding rough...like its missing a cylinder. I should have changed out the wire harnes also but did not at that time. I am having difficulty finding the proper harness or even knowing what it is called. I don't want to purchase the wrong harness. Does anyone know what he wire harnesses are called that come off each side that plug into the individual coils?

Thanks,

[Infinitiexpert]

I have never seen a bad harness. Most likely the problem is one of the injectors.

[F50Qship]

How many miles on it? I would also clean the MAF and apply some dielectric grease on the pins. I would aslo recommend cleaning out the TB and IAC valve. You can also ohm the injector connector harness. Ideally, it should read between 10 - 14 Ohms. If not within these range, injectors need to be replaced. Bi-weekly I have been Ohming both my knock sensor and injectors. Although my injectors were replaced 10K miles ago and KS 5K miles ago.