1995 Ford Explorer O/D light blinkin

I just bought my first car and its been working perfectly fine until just now. The o/d light has started blinking and its been doing so non stop. The car runs fine except now its harder for me to accelerate once ive stopped. The panel that shows the rpms goes up all the way to three and drops back down but the car seems to go slower. I did a little reasearch being that I dnt know much about cars but most of my reasearch leads to the same conclusion. The torque converters. So I need a little help before I go overboard spending money on something my car doesnt need fix. A liitle help plz
thanx in advance