You may have some valve body valve/gasket or servo problems.
Has it ever been worked on or any shift kit stuff put in it.
Make sure the shift linkage inside and out and shift valve is centered good.
And drop the pan and check for any extra metal or clutches in the bottom of pan
Also get a transmission capable scanner on it and check it out good on the computer stuff and codes.
Here is a link to a good transmission forum if you want to run a post there and ask for transman he may have some more ideas on it.
http://www.batauto.com/Forums/index.php?board=5.0
Good Luck
MT