I have a Mitsubishi Galant 1997 with a 4g63 Dohc swap (from a 2006 mitsubishi outlander). The swap itself was more or less plugg an play, with some minor tweaking to the wiring. Other than that it runs perfectly well. The problem is the idle. Even before i swaped out the old engine the idle was kinda "wonky". It either runs too low (100-400rpm), too high (1700-2500rpm), jumps between 1200 and 1800rpm or is kinda normal at 1000rpm. It used to "jump" when letting off the gaspedal, but i adjusted the TPS and now that is gone. I have replaced the IAC sensor and MAF sensor. Checked for vacuum leaks with brake cleaner, and there is nothing. The airfilter is not clogged, because i replaced it with a cone filter. I can't use an OBD2 scanner on the car, because you need some type of "special reading tool" I have not found out what the problem may be yet. I suspect that the ECU may start to get too tired from old age?

Any advice is apreciated. Because it is realy anoying with a straightpipe when on parkinglots and such. Get a lot of people staring.