Your motor is trying to pull more curent than the battery pack can supply - the voltage is dropping under load to below the level of the LVC - the LVC then works as designed and shuts the motor down - when the throttle is backed off, the voltage increases again, and you start over.

You are way overpropped for that motor - an extraordinarily irresponsible review article in Nov 2004 Fly RC discussed exactly your set-up - 15A at WOT!! The motor is only rated for 4-7A, max of 8A/60sec, yet the reviewer reported flying for 12 minutes at an average draw of 7.5A!! He was using Kokam 1500's (rated at 8C = 12A) so he was overtaxing those too!!

Those TP 860's you have are presumably Gen 1 (6C) - if so they CANNOT hope to supply that sort of current safely.

Cheers, Phil