I just completed my JDM swap, replaced clutch, And bolted on a HS header. The car runs great except cruising at a steady speed. For some reason the little nightmare wants to surge, but only at a steady RPM and just SOME of the time. Accelerating and decelerating are fine, almost too fine. Any Ideas as to the cause?? FYI: no MIL light illumination so I'm hesitant to believe it's serious, just very annoying!!!