I can't seem to figure why my motor is running so rich. It's fully rebuilt new everything brand new head. I've changed cap and rotor, plugs, wires, coolant temp sensor, and checked al vacuum lines. When the car idles it seems to stumble a little bit and the car is running so rich it left black residue all along the rear bumper. If anyone could help me solve this it would be much appreciated!

Is it boosted?
Is there a check engine light?
Are all of the sensors new?

Not boosted no check engine lights and only the coolant temp sensor is new I think and I just replaced wires again today and injector o rings and its dumps black smoke around 4500 rpm and up