my first thought would be oil slosh on braking. a lot of the modded pans Ive seen over the years concentrate on keeping the oil near the pickup on launch and during a run, but don't really consider where the oil will go under hard braking. is it a specific brand of pan or one that's been modded up?
One of the things I've seen/read about being done to decrease forward slosh was a hinged baffle that would allow it to run back to the pan, but act as a barrier in the front half of the pan to keep the bulk of the oil around the pick up. windage trays can also sometimes help depending on how its designed.