don't know your mileage, but i would suggest draining the whole tranny, changing the filter, refill(about 12-13 qts) using mercon V and ford friction modifier, and i bet that will help. mervon V is safe in the aod...i have been using it for awhile, and others have too with no complications. just make sure you get ALL of the merc. III out first.
2003 Ford Expedition: 5.4L, harley supercharger, 2.93 upper pulley, 4lb lower pulley, c&l plenum, jlp cai, LFP SBTB, FTSP, Magnaflow 3" catback, Eclipse AVN-5510, white face gauges, cobalt c2 boost gauge, ddm hid's, 379 rwhp, 465 rwtq sold 11/3/12
2009 Ford Flex Limited AWD