It could be you are running out of vacuum and it's setting a DTC 61 intermittently ?? You said hard run to 6+k rpms, and that would be where the manifold vac drops almost to zero and in theory our vacuum pump is supposed to pick up any shortage of vacuum in the system to keep the 2* actuators pulling on the 2* linkage.
Not to be a wise guy, did you use the Gordon jumper for the CCM? I think that's where the history codes and intermittent codes are stored....I think!
Tom