Torque converter locking and unlocking?

[hypocrisyB]

For some time now my 4r100 transmission has been acting weird. If I'm driving around in overdrive at highway speeds and give my truck a decent amount of gas the torque converter seems to unlock and lock several times. It'll build up the revs a couple hundred RPMs for 1 second and then drop back to where it was...then it'll do it 5-6 times and then not to it for the duration of my drive.

If I shut my truck off, turn it on, it'll do it all over again. But once it stops doing it, it'll be fine for regardless of how many miles I drive. Otherwise, the transmission is fine. I towed a 12k lb trailer 75MPH the other day and everything was fine.

I recently got a DP-tuner chip but the the transmission had always been a little weird even before the DP-tuner chip.

Thoughts?