Help

i have an 87 hyundai excel 5 spd. 4 dr. sedan. it does this thing where it won't go into gear especially if im on an incline. when im at a stoplight sometimes and i go to put it into first its like i have it in neutral. i doesn't go anywhere. neither can i put it in reverse or any other gear i have to wait until it goes. at first it only did it when i was stopped but now it does it if you're going down the road but usually only on an incline. for that reason i stopped driving it. but the car im driving now is costing me way too much money to drive (gas). so if anyone can help please do. THANK YOU