black soot on the spark plug

Ok so i have been chasing a ghost for the past three weeks. I have a idle problem its rough. So i changed iac,tps,spark plugs,wire,cap,rotor, cleaned throttle body. No codes, runs fine once driving. So here is the issue, just took my plugs out, after only drive five hundred miles, and notice alot of black soot on all the spark plugs. What does this mean, does this mean that i have a rich running motor or is it telling me that the cause of the rough idle is because of somthing to do with the soot on the spark plugs

What brand of spark plugs?
Year etc of your Jeep?

1996 jeep put champion plugs in it

Sounds like you are running rich.

1. Check fuel pressure. Must be done with a gauge, no shortcuts. For a 96, should have 49 psi, plus or minus 5 psi. Many parts stores will rent you this tool inexpensively.

2. Test MAP sensor. That sensor is involved with fuel/air ratio. You'll need a meter and a manual. Be sure vacuum line leading to that sensor is pulling good vacuum.

3. Oxygen sensors have a lifespan of between 100k and 150k, depending on efficiency of the engine. If yours are old, swap them out as they aren't particularly expensive and they get "lazy" before they will set a code. I look for NTK brand oxygen sensors