Missing at idle, sputter when getting up to speed?

I have replaced the EGR, O2 sensor, MAP sensor, distributor, coil, ignition module, plug wires, and plugs. I have the Howell GM TBI fuel injection kit on it. I am getting error code 45 which means I am running rich. The fuel pressure is 11.5 PSI and that is in the range per Howell. Tech said 11-12 is good to go. I have not checked the return fuel line pressure and I have not checked if I need to upsize the return line as I am still using the stock return line. I am also wondering if it isn't a ground or wiring issue. My radio and oil pressure gauge have stopped working and this has all been going on for the last two or 4 months.

Thanks.