NXSLT1

I've got a 96 T/A LT1 OBD1 conversion pcm with a roots blower on it and I can't get it to run right. I have no clue what I'm doing when it comes to tuning these computer cars. The car spits and sputters and backfires when I open the throttle (this is sitting still in the garage) then blows a big puff of black smoke out of the tailpipe like it's pig rich. If I ease into the throttle it doesn't do it. First, would the stock map sensor make it do this since it doesn't read boost and second do I need a 2 or 3 bar map and will it work with the stock ecm or do I have to do like the LS1 guys and get a custom OS for the ecm??