unburnt fuel?

i'm new here so i would like to say hey to everyone.

i have a 94xj that i rebuilt- 30over, stage II mopar performance cam, header, 2½" custom exhaust, hi flo cat, 62mm tb & spacer, fms 24# injectors, k&n filter charger, jacobs electronics ultra team ignition system w/ accel splitfire plugs and i also had my computer chipped by ase.
i noticed that i have a ring of black soot around the outside of my tailpipe and asked a jeep mechanic about it and he said it was unburnt fuel, his suggestion was to replace the O² sensor- which i promptly did as well as sand the black ring off the tailpipe. well the black ring is back and i'm baffled. from researching this and other jeep websites it seems with the mods to my engine it should be very capable of handling the 24# injectors. does anyone have any thoughts on this? i'm open to all suggestions!

thanx in advance

My '97 does the same thing, but I havent done any modifications to it other than a cat-back exhaust. But, then again we may have something in common. My cat is almost completely rusted out, you have a hi flow cat. Perhaps our cat's aren't picking up all the carbon that is produced when the fuel actually ignites. Does your exhaust smell like gas? I know I've smelt some cars that were running rich and the smell of gas is overwhelming. I don't recommend you actively sniff the exhaust, it'll kill you. Just "woft" the air.

yes my exhaust does smell of gas

Jus Put a Spark Plug in the tip of the exhaust, that get rid of that extra fuel!

Ok, then you should try adjusting the MAP sensor. There are lots of writeup on for how to do it. Dr.Dyno has a good one I think. Just run a search for MAP Sensor. Basically what you will do is make a simple electrical devise that you can use to fool the computer into thinking that the Jeep need more or less fuel. Not only will this probably solve your problem, but it will allow you to fine tune the air/fuel ratio of your Jeep allowing you to get the most horsepower possible.