From other things I’ve since read, not being calibrated the sensor causes it to limp, not going over a certain rpm.
Strange they have to do that, imo: There shouldn’t be any reason for it if that part of the design was tight. It isn’t like they are landing a person on the moon where you care about small fractions of errors in instrumentation. This is a half-an-axe-handle car, for crying out loud.
Anyway, reading some more on this procedure, not being calibrated does not seem to cause what you’re seeing. It seems to just go into limp mode.
Good luck with it. Report back on your findings. No doubt, between all the gear heads on this site, we’ll get it up and running again.