what can be causing black smoke to come from the exhaust during acceleration? on 1991 Buick Century

it just started happening, but only seems to occur when the throttle is pressed, either from driving or from pressing the linkage from the engine

Asked by for the 1991 Buick Century
Engine is running rich! Have the fuel system componets and related sensors tested!
I cleaned the throttle body and the MAF sensor and that seemed to help a little bit
2 more answers , 1 more comment
Agree with #2, to much gas.
that was one of the first things I noticed was the poor gas mileage, that 3.3 was sucking it down like a v8
Could be anything
Is the smoke grayish white smoke?