I'm using my ignition wire from the ignition switch to power a relay that turns the MS on and off...the power to the relay and to the MS comes from the batter, a redtop Optima. I also use a noise filter cap on the power supply line. I played around with it more today, and its still doing it. From an overnight cold soak, it warms up to op temp, and it runs great, ego correction is +/- 5%. Shut the car off for a few minutes, and it runs really lean until o2 correction kicks in, then the ego correction gauge is reading +8 to +15%! i dont get it..I even swaped in a new processor, same thing. Other than that, its running great :shrug