2.8Ls have solid lifters and need relashed every so often (40K?).
Black smoke is usually too much fuel. The fuel systems on these engines can be prone to problems. People tend to go with a duraspark conversion and 2bbl carb, but it is kind of expensive and may not be able to get away with it depending on your emission testing / laws.
1987 Ford Ranger Short Bed 5.0L/T-5 Project
1988 Ford Ranger Long Bed Parts Truck
1993 Ford Tempo 2.3L OHV HSC Auto - D/D Stock.
1999 Honda Accord VTEC Auto
2002 Dodge Caravan - 3.3L Auto