Ford Repair: Ford Expedition Trans, metal shavings, arizona desert

Question
Jason,
Hello. Hope you may have an idea of what is going on w/ my 2001 Expedition. It is the 5.4l w/ a tow package. We never tow w/ this car, so it has never been put under stress from towing.
My problem is that at least 8 different times the trans has blown out quite a bit of fluid, ensough top where it leaves a line in the street that I can follow back down our block. I leave it set and it is fine for a while (months).  It just did it again today again, alot of fluid in the drive way and street. I seem to notice it is doing it more when it is hot weather.  
I usually drive it around the block and check the trans fluid, and it is usually ABOVE the "ADD" line.
I have had this to 2 diffent Ford Dealers w/ them finding nothing wrong. One even opened the tranny and said all looked good, no metal shavings inside.
I know this isn't normal. Any help would be great, as I will be taking it through the Arizona desert in a few weeks and I am sure the temps will be over 100.
Thanks for the time.
Daren

Answer
That is really strange.  It's possible that the transmission cooler is restricted, that could cause pressure to build up and spring a leak.  I would make absolutely sure it's not over-full and maybe have a shop flush out the cooler lines (pretty simple and inexpensive procedure) and if it continues to act up, it's possible that the transmission itself has an internal problem.
I will look into it more and if I come across any other possibilities I will let you know.