904 question. Please help.

Have you checked all around the belly of the tranny to see/feel if it might be coming from the vent area, or is it literally coming out of the dust shield area/vent, as you know most of the time the car is in a forward motion, so the fluid won't go in front of its origin of leak, it'll blow back, if all of the top & sides are dry above the pan, i'm sure its not coming from the vent, take the dust shield off & see if theres fluid on the inside area, this will pin point it too the front seal.

If it ONLY happens under hard throttle, its very possible its pushing past the front seal do to increased VB pressures, you 1st. need to make sure its not over filled.