my o/d light was flashing yesterday ..and i checked the transmission fluid and it was on the bottom dot so i added a quart...could that stop the light from coming on?

Sounds like you have a bad engine speed sensor. Also called a VSS (vehicle speed sensor)

Transmission fluid does not evaporate, you have to have a leak. My daughter's 99 explorer had the same sympton. It was the connections where the transmission lines enter the radiator for cooling. Both are on the drivers side on radiator, one near the top, the other further down. Check there first for a leak. Then look under the vehicle for fluid. If there is a leak it will be all over the bottom of the engine and transmission. Have the tranny serviced with a new filter and pan gasket every 40K.

Could also be a solenoid or servo. On the 96 there was a head shield deflecting heat away from the transmission servos on the tailpipe. Check if your's suppose to have one and see if it is still there.