Stock engine with cam

[yeah758]

I just bought a 88 GT that already had the mass air conversion done to it. It is a god only knows how many miles motor that is completely stock except it has a aftermarket cam. My problem is it runs very rich. It lets out a cloud of black smoke when I get on it and is extermely rich at idle. The only codes are related to missing smog pump and thermatcor (sp?) valves and from the conversion 81,81,95. Do you think it is the cam or shoud I look somewhere else. The guy I got the car from had no clue how to work on one and I spend most of my time undoing what he did. any help would be appreciated.
PS the bap sensor was dead code 22 I replaced it and the code went away but it still runs rich and slow