93 concorde..HELP!!!!!!!

3.3 liter. just installed used engine and can't seem to get all the kinks out. seems like there's a timing issue. keeps backfiring and spinning over and eventually cranks but it floods the engine. i've changed the computer, the fuel pressure regulator sensor, camshaft sensor, the fuel rail, plenom, and injectors. i just dont know what more to do. can someone give me some ideas. please....