Saif Auvi

Hi All,
I am new to this forum, I would like to share my serious problem on my 2005 Honda Civic Ferio ES1. Please help me if possible.

I bought this car 3 months back, It had a D15B(not V-tec) engine with SLXA Automatic transmission, after driving only 7 days my transmission got failed. So I searched same transmission in my country but didn't find any. Then I have found one engine D15B-Vtec with MLYA transmission. I have bought and installed it. Sorry to inform that I am not that sound with any Honda engines and transmission. Now after installing this D15B-Vtec with MLYA transmission my expert said you have installed wrong transmission, it will not work here properly. I got nervous and scared, then he said I will try to fix it but not sure it will worth it or not. Now he has worked on it couple of days, and said I need a AFR sensor for this engine, so that he can calibrate the transmission. Unfortunately I had to install my previous engine's O2 sensor because with this new engine with MLYA I did not get any AFR sensor from the shop I bought the engine. Now I have ordered a AFR sensor from China part no: 36531-PLE-003. which is still not received.
I wanted to know, do you guys think this sensor will solve my problem as my expert said to me?

Pls note, This new Engine D15B Vtec I bought, which came with a MLYA was from a 2001 Honda Civic EU1 version.

My car is not working, RPM goes up and down on idle and car engine turn off while I push the brake sometime. gear box is behaving very abnormal while I release the gas paddle. Pls help.

Thanks