Won't shift out of park on 1996 Geo Tracker

Sometimes when I go to drive my car it won't go out of park. This has been happening of and on for about three weeks. After messing with it for five - ten minutes will work again. Anyone know what I should do to fix it, I'm a poor college student so I hoping to be able to fix it cheap.

Asked by for the 1996 Geo Tracker
could be your Brake Safety interlock switch located at your brake pedal,switch costs about $25 and is easily replaced...
could be a fuse controling stop lights also easily fixed for the cost of a fuse....
could be the shift lock safety linkage cable, alittle mor work to fix, however check to see if you have an override fix, this is a small hole in the upper right hand corner of the center console where the shifter is, take cover off and insert small screw driver to over ride the lock.
1 more answer
I had the same problem. We checked all of the possiabilities listed in the prev. post. We even ordered the break switch, it still wouldn't work. Finally, we figured it out. the shift knob was not screwed on tight enough. I guess after years (14 of them) it just became to loose for the cable to activate completely. Turned it to the right until it was snug and it then would shift to Drive.