Azlar

I have a 1998 Explorer 4.0l Auto and the other day reverse gear suddenly stopped working. All forward gears work fine it just seems to be reverse. After it had stopped working I tried again a couple days later and it worked briefly, up to the point where I accelerated, it then just revved up.

Could anyone offer a suggestion as to the cause of this, I have some mechanical knowledge and would be willing to try to repair it myself if it isn't overly complicated.

Thanks in advance.