93 Chevy S-10 Blazer runs crappy. 4.3 vortec

I got this truck for 100 bucks, great condition, the guy said the motor was locked up, I took it home, it wasnt, a batt. Cable was loose, it ran rough, the heads were blown, I fixed that, it ran fine for 2 weeks, then the check engine light would come on, it idled rough, ran rich, stalled out, wouldnt start, I ran dionogstics on it, a map sensor code, iac code and a tps code, I replaced those and the o2 sensor and the plugs, the touble codes are clear, but it still runs poorly, I ran a compression check, all 6 cylinders are within specs, there is no water in the oil or vice versa, can anyone know how these vortecs, work, thanks :x