Found vac leak, still not running right

[nimixes]

Hey guys. I have a 89 GTR that had a bad vac leak and was driven for a bit. I found said leak and fixed it but the car is still running really rough and rich. It's all stock save the exhaust and apexi intakes. Cleaned out my mafs while they were out and hooked everything up properly again. When I looked at my tail pipe there was some really heavy black soot coming out of the tail pipe. I'm thinking I may have soaked the plugs by driving it with the vac leak or it could possibly be some buildup in the system from driving it rich for a bit? I'm curious what you guys think.


Here's a pic of the soot that came out.

[nimixes]

Looks like the problem...

[Skym]

Check o2 sensor voltage, as could be lazy (sensors themselves could be fouled, just like the spark plugs) making ECU make engine run too rich for too long. Popping sound from exhaust is one symtom of this.

If unplug o2 sensors and it stops, then have found the cause. But be aware that sometimes the o2 sensors can be compensating for a intake manifold or similar air leak. But if that was the cause, then the rpm would be going up (lean) and down (rich) at idle.

The other is stock ECU is using knock maps that run the engine richer. Sometimes the knock sensors pick up false knock (something banging against engine or internal problems with engine).