rough idle issue has me stumped

[roverguy10]

Slightly rough idle especially once warm. All plugs are sooty black, with the exception of cylinder 3 - it is wet. Codes are only showing bad O2 sensor on the driver's side bank. I've replaced the coils twice (long story), plugs are Champions, and wires are brand new Kingsborne.
I'm thinking its either a leaking injector or bad ECU. Engine had a small fire (ACE pump, another long story) and this problem has been present since - entire engine harness was replaced after fire.

Any ideas, thoughts, things I can check?

 

[96discoI]

IACV, TPS, MAF. fuel pressure regulator, fuel pump, vac lines for fuel, VSS. there are many combinations of possibilities,good luck

 

[listerdiesel]

Change the injector on #3 first, it's the most obvious and quickest (relatively speaking!)

Peter

 

[Keanan]

Change the injector on #3 first, it's the most obvious and quickest (relatively speaking!)

Peter

Or at least just swap it to a different cylinder. If the other cylinder is wet you know it's a leaking injector. If it is dry and #3 is still wet you have other problems.

Any vacuum leaks?

 

[scottagnew101]

This sounds a lot like what I'm experiencing, I was just going to run some sea foam deep creep to try to fix it. Good idea, bad idea, or other?

 

[archaeology_student]

Similar issues for me, but I know I have some big issues.

1. Rear main seal is leaking
2. Gaskets are leaking and allowing blow by to happen, therefore, oil is leaking into the engine and mixing with fuel.

I changed my all plugs and wires, and he ran smoothly for a few months... then plugs were filthy again

 

[RoverbyProxy]

Why don't you believe that bad plug wires and o2 sensor is the problem? A bad O2 will cause the engine to run rich and faulty wires will explain the wet #3 and stumble.

What rig do you have?