In automotive applications the throttle controls engine load (torque) - not rpm. RPM is controlled by the transmission.
Skipping injection is a good strategy but the WBO2 will read lean due to the unburned O2 from skipped cylinders.
You need to map injection quantity to engine speed. Target a rich mixture (lambda approx 0.9) at full load and lean (1.1 - 1.2) at part load. That alone will reduce the output by about 20%. Depending on engine design you may be able to go a little leaner. Note that lean mixtures will require more spark advance. The WBO2 will give useful readings throughout this range.
Once you have mapped the entire load - speed range (from 80% to 100% load) you can produce the 0% - 80% region by mapping your skipping strategy. Injection quantity and ignition timing will be the same as 80% load at each speed.