Sorry if this has already been covered, do you have a pull up resistor on the crank sensor? I fought mine when I originally put the car together. They have trim pots inside the ECU, but they didn't do anything to help my signal. Once I put the pull up resistor in the circuit, the problem was solved. Also, how is your trigger wheel mounted to the crank? Is it on the back side of the pulley? I have mine welded to the back of the pulley and one time my engine would start breaking up around 5000RPM, almost like a rev limiter. I later found one of the tack welds had broken and I guess the trigger wheel would get to moving around at the higher RPM. It ran perfectly fine at lower RPM.