I just bought a 1995 4 door integra that has a 2000 engine in it. They just swapped the engine about 2 weeks before i bought it. The problems im having is the oxygen sensor on the 2000 engine will not connect to the plug on the car because its a 95. Shouldnt they have put in the 2000 wires with the 2000 engine to make the sensor fit right? Im also wondering if they changed the ecu in the car, because with the car warms up the idle revs up and down up and down. Is there a way to check if the ecu was changed? ( a certain number to look for on the ecu or something?) and is there a way i can plug in the oxygen sensor ? [if need i can take pics of the engine and plug if you think you can help me or give me advise.] The check engine light is always on and the car runs a little bit hot.