Intermittent problem with bang shifting?

Well heres the story, I have a 1995 Explorer 4x4, and starting last month I have been having an intermittent problem with bang shifting, the only time the bang shifting occurs is when the overdrive off light flashes, the only time the O/D Off light flashes is after driving the interstate or driving around town on hot days, after a few days or a few weeks the light turns off and its shift normal and no bang shifting, but I have a new problem now, the O/D Light off started flashing last night after driving the interstate and I noticed on my way home that it wont shift into second properly, it hit 4000rpm and I had to release the gas and it would then shift. The bang shifting no longer occurs, seems to be very quite when shifting, now I just need to figure out how to get it to shift into second properly and I would like to be able to fix it myself since I am on a tight budget and cant afford a new trans or have it rebuilt, also I took the negative battery terminal off and the OD light no longer flashes but I do still have the problem with shifting.