Well, here is what is going on.  I bought a 2006 Grand Prix GT in
May.  Since I have had it, it will from time to time disengage the TCC
and immediately re-engage.  This only occurs while cruising.  It does
not matter whether I just left for work or have driven a couple
hundred miles.  With that, of course, the tranny temp does not
matter.  This will occur at a wide range of cruising speeds as well.
I can tell you that it seems to occur less when the ambient temp is
lower.  Not sure if the IAT effects the tranny control at all (other
than effects to the TP).  I am curious if anyone else has this issue.
I almost wonder if it is bumping against the lower TP thershold for
TCC dis-engage.  If so, I would think I could easily google this
issue.  I almost forgot, there are no stored codes.  I have cleaned
the harness connectors.  Brake switch is not the issue.  Tranny fluid
has been changed.  Fluid level is correct.  TFT is within TCC range.
This occurs on level driving surfaces.  It really is annoying, and no,
it is not a miss.  While cruising, the RPMs jump up a couple hundred,
and immediately go back (as with TCC engagement) with no changes in
speed.  This happens very smoothly, but I can see it happen, so it
bugs me.  Any help would be appreciated.