I hope I'm posting this in the correct forum. Sorry if I'm not. Anyway, the car is a 1993 Dodge Daytona ES 3.0 V6 Automatic transmission. When I start the car and put it into drive, it goes into drive. I start driving and accelerating, and it smoothly shifts into 2nd. Accelerate more, and it smoothly shifts into 3rd. Going about 50 mph. Slow down to about 35-40, and it shifts/jumps hard back down into 2nd and stays there when I accelerate back up to around 50. If I slow down enough to where it should downshift into 1st, it doesn't. It just stays in 2nd. If I stop the car completely, put it in park, shut it off, then restart it, it will do the same thing over again. No lights come on in the dash, and it's full with fluid with no leaks. I can turn a ratchet for extremely simple stuff like an oil change and brakes, but I am BY NO MEANS an auto mechanic. Help please!

 

Probably time for a transmission service.. Take it to a shop for a diagnosis. You dont mention mileage or maintenance history, so one can only guess it's time for some type of service as its 25 years old.

 

Agreed with jkeaton, change the fluid/filter.
Use ONLY a Mopar filter and ONLY ATF+4 fluid.