RedEG-6

I have an LS swap on my civic, it is a B18B1 1998 OBD 2 motor. I used the engine harness from the LS OBD 2 motor into my original OBD 1 internal harness to the computer, gauges, etc. I am using a P05 computer, i was told that computer was from a Civic CX. I basically got fucked over by some *******. The motor doesn't feel like it has the power it should and it has a rev limit at 5,800 or 5,900 RPM. Another thing is I have a check engine light, it is throwing one code, code 41, which is O2 Sensor Heater. i was thinking of replacing the O2 sensor and getting a 94-95 OBD 1 Integra LS ECU. Can someone please help me and tell what i should do with this situation, i will really appreciate it.