Tailspin Turtle...
the bleed source would switch back and forth, resulting in "uncommanded thrust changes in condition PA". It was apparently solved by eliminating the automatic switching feature.
Must admit it's going back a long time and my memory might be playing tricks but I have the hazy recollection that the F-4Ms (FGR 2s) retained the feature but with the option to switch it off or manually overriding it.