My 1995 explorer has the check engine light on,

my 1995 explorer (192k miles) has the check engine light on, and the o/d off light flashing, but when i took it to get the codes read, it just said error and wouldnt give the codes. whats the deal? it has been this way for 5 months, doesnt want to shift from first gear to second, unless i let off the gas peddle, then slowly get back on it. hasnt gotten any worse over that time frame. i had bought the truck 2 weeks before the problem started.