ok heres the thing sometimes when going down the interstate i can punch the car and it does not shift down into the lower gear like it is supposed to and sometimes it does its like it has a mind of its own or other times when i am in town i can push the button to turn off the overdrive and the button thing does not work and sometimes it does do i need to change a sensor or something could somebody please help me

 

It sounds kind of normal to me. Do this, while on the highway or interstate, below 70mph preferably, and push the button turning it off. Your car's RPMs should jump up and your O/D light on the instrument cluster should come on (or go off, I forget, sorry, regardless, it'll do the opposite). In the city, you don't really notice the o/d being on until you hit speeds exceeding 40+ (depending on how fast you're accelerating).
When was the last time you or the previous owner changed your transmission fluid/purge/filter change? What color is the tranny fluid, does it smell burnt (if you don't know what clean tranny fluid smells like, skip that part)? I know, they told me not to smell the vials in chem class too, lol.

*edit*
Make sure to use MOPAR tranny fluid on that a604 because it is VERY picky with it's fluids.