OBD I to OBD II Conversion Issues

Test drove the car with the VSS and O2 sensors unplugged. Was able to get up to speed without it cutting out, so that theory was confirmed. I unplugged the O2 sensor because it seemed like it was leaning out. Now it is extremely rich, not surprised. It also fumbled on acceleration, backfiring through the intake under load. I'll figure what is going on with the O2 sensor wiring and see how it runs.