fuel problem

Alright my 83 eldarodo wont go above 40mph on the freeway...can hardly make it past 15 mph goen up a hill. When i start it up it leaves black marks on the ground and blows out a lot of black smoke. There is a lot of unburnt gas anyone of any idea what it is? dis/plugs all are working. I'm thinking a sensor? or maybe a vacuum leak? or maybe its the ECM all together?

Timing?

I believe your car has the 4.1-Liter fuel injected V8. How does it idle? My guess is that one or more fuel-injectors are leaking/dumping fuel, which is why you see black smoke or unburned fuel. Pull the spark plugs. If some plugs are clean while one or more are carbon fouled this indicates too much fuel where the fouled plugs are. You might be able to pinpoint bad injector(s).