did u reset ur ecu by disconecting the battery before ecu swap.If not try.

 

yeah, the cosde is there

 

sounds like ecu is going into limp mode. could def be from the o2 sensor. if the ecu doesn't read the AF, it's not gonna know how to adjust fuel in closed loop

 

if your front o2 sensor is bad the O2 will go into limp mode. Its backfiring because its running so rich to protect the motor. In limp mode the engine rev limits and adds a ton of fuel to save the engine. Replace the front o2 sensor with a new one, and reset the ECU you'll be set.

 

Problem solved, i got a k-pro today, and the engine is runing nice. I still need an o2 sesnor, but ill deal with that later.
thanks
Cuervo,A