Auto trans wont change gears speedometer jumps up and down

Have you checked the fluid level? if not do so with engine running in park and e brake pulled Also look at the fluid is it brown in color and smell sort of like onions? if it does it needs a filter and oil change. most cars require the filter and oil to be changed every 30,000 miles. Also add Lucas transmission additive so that it will soften the seals and clutches. If you want to do this yourself let me know and I can give you instructions, however it can be messy. the transmission will take 12 quarts of fluid dexron III and the lucas oil conditioner. Write back if you need more help and thanks for using fix ya.