95 ford explorer o/d light please help
 

hi i got a 95 4wd 2door explorer and the o/d light keeps blinking the trouble i am having is that when i take off in first it is allright but have to let off the gas to shift to 2nd and shifts find the rest of the way but when i am going at a steady speed and keep it there it feels like i am feathering the gas and i am not what could be causing this problem thank you apppreciate all the help