I purchased a 2001 Impreza RS with a 2004 WRX swap already started. There is something wrong with the wiring, because the engine light is on, and says that the cylinders 1 and 3 misfire, then I'll get a code down the line saying cylinder 2 and 4 misfire. When I unplug the MAF sensor, the car runs better and doesn't bog down, where as when I have it plugged in, the car loses almost all power, no spool, and has a terrible misfire. I've replaced the MAF, IACV, Oil Breather cover on the right side valve cover, wastegate actuator, PCV, and I noticed I have a large amount of gas getting in the oil with the misfire and loss of power. I'm hoping this information can possibly make it so you can come up with some ideas of what I can look for.