coverter lock-up

[86SS86LS]

While cruising, the torque converter locks and unlocks randomly - this usually happens within the first few miles of my commute and then goes away. What could be causing this?

 

[WSLN 6]

TCC lockup solenoid in tranny, or maybe the brake switch is misadjusted causing it to lose it's 12 volts here and there.