I have had an engine swap done on my 2000 Galant but I did not think to get the wiring harness of the computer for the I swapped I just used the existing parts from my Galant. The issue I am having is that my check engine light is coming on with the code P0170. Which is that my fuel trim is running lean. After numerous repairs I found that not getting the computer and the wiring harness for the new engine could be the cause of my problems. I have taken the car to the Mitsubishi dealership a few times and they have found noting wrong...thats because I had failed to tell them that important information about the engine swap. The engine is from the year 99-03 not sure which specific year. Another issue I am having is that my temperature gauge is not registering correctly meaning 10 seconds after I start the car the gauge is near the middle which is impossible because I have replaced the thermostat, Temperature sensor, and new anti freeze. It is a lot going on but I need some help on how to repair this issue once and for all.