The little black smoke is unburned fuel when under load. Generally not an issue just means the engine is getting a tiny bit more fuel then it can consume at the current speed. Or to put it differently its just lugging along and adding more fuel will not make it lug any faster so it goes unburned. If it does it alot you need a tune up or smaller injectors unless you like rollin coal
Coach runs, usually,Toad runs almost all the time
We get there somehow every time, Go Black Betty!
1990 CC Concept Dragging a 2000 wrangler