97 EB Explorer transmission problem
 

I have a 1997 explorer with the 5.0 motor and all wheel drive. It has an easy 150K miles on it. A year or so ago you had to let off the gas to get it to shift into overdrive. The problem went away as soon as i drove it to the transmission repair shop. The problem has returned again and this time it is all the gears. If you don't let off the gas it will never shift until you get over 3000 rpm's. I had the fluid changed along with the filter, no flush. Any help would be greatly appreciated...