Rev-N-Nator interference

I fail to understand how EFI in open loop operation causes an ignition problem. Since it goes away in closed loop that would suggest tuning issue in fuel table, or other setting and that is dropping RPM, not the ignition. Closed loop is correcting (making adjustments in fuel) for the incorrect open loop setting(s).

The EFI system controls the pulse width and rate of injectors, noise from that would have to be really bad (FUBAR), to result in an ignition problem, and would not go away CL.

While the RPM drops 1000 RPM, that by itself is not enough to further diagnose. Fueling issues are related to RPM and MAP values, so observing those, where fault occurs will indicate the area where the tuning problem exists. I am not experienced with Terminator, but there should be ways to datalog and find exactly the difference in fueling between OL settings and what happens CL. Also what is the AFR gauge indicating when fault occurs?

Settings related to time/temperature for warm up conditions might be askew, resulting in RPM drop. This is only a guess to since original post does not indicate enough detail about engine operating conditions when fault occurs.