Transmission problem

[SRJesse]

Just bought an 89 240sx with only 95,000miles on it. There is something wrong with the transmission, but hopefully its just low on fluid, I haven't gone over anything with the engine yet.

The problem is it acts like a car with a clutch, when I let off the gas the rpm's drop to idle and then it revs up to where it was left off. (really strange) It also doesnt downshift when you floor it. Almost seems like its only working with one gear cause it wont downshift. Please let me know if you have any idea what could be wrong with it.