I dropped a b18a1 into my 90 civic hatch DX over the weekend and it went pretty smoothly until I started it. I did a mpfi conversion on the stock dx harness and converted the dizzy plug and everything and it will start and run, but it is running WAY too rich and it wants to die when I let my foot off the gas. It is also hunting and surging. I did a continuity test for the orange and white wires on the ecu, the two white wires on the harness to make sure they are in the right spot, and the blue/green and blue/yellow wires on the ecu. All the wiring is correct, but I just cant figure out why it is running so rich and crappy. I can drive it down the road, but its hard to keep it alive. Can someone please help me? There is a green plug on the back of the motor towards the bottom that doesnt have anything plugged into it. There is nothing on my harness to plug into it so I thought I didnt need it...but I found the plug on the LS harness that is supposed to go in there. The wires coming from it are white/green and black. Does anybody know what it is and what it does? The mechanic who helped me says if it is a temp sensor, then it needs to be plugged in or the computer thinks your car is always running at -32F and will dump a bunch of fuel into it to compensate for the cold weather. Does that sound familiar to anyone? Or can it be a vaccume issue?