If you have a new ECM you have lost your S&S download. You will either need to get another download (I assume your download card is gone) or you need to get a fuel controller of some sort. It will be very lean with the stock download and your airbox and pipes.
110 Cubic Inches -- S&S stroker crank/Lloydz Big Bore, 11:1 Wiseco pistons, massaged stock
heads, Lloydz VM-1-HP cams, S&S valve springs & retainers, Torque Tubes intake, stock throttle
bodies, RPW Thor pipe, Lloydz ECU, PC-III, Rivera Pro clutch spring, 31 tooth pulley w/Buell belt.