VX engine swap

[1992VX]

Hello everyone....

I'm trying to solve a problem with my 1992 VX. It racked up 556,000 KM on the original motor and finally the 11% grades on the Gaspe killed it.

I replace the engine with a D15B V-tec 1500cc (Japanese Domestic Market) that produces 130 HP and is downright scary in terms of power. (the old VX was a D15Z1, still a V-tec but the E version with 92 HP ) and back then Honda hadn't coined the term V-tec.
The catalytic converter was also repalced but they left the O2 Sensor from the original motor. It too was "cooked " a couple of years ago.

The motor ran rough at constant speed but fine at idle or acceleration or at high RPM( similar to the "bucking" thread I read on the forum), I too plugged the vacumm hose on the EGR valve but it didn't affect it. I unplugged the O2 sensor and it ran great....but the engine light is on. So I went through the expense of buying a NGK 5 wire wideband sensor ($ 300 aftermarket) because theVX ECU (P07) requires it.
Same problem! I unplugged it and it runs fantastic. But, even though I can get 620 KM of city driving on a tank, I think I can do better if the sensor functions properly; also I need this hooked up to pass an e-test and don't want to pollute.......did enough of that with the old motor.
I think my AF ratio my be too lean for the new engine?
Any comments?
Thanks