Transmission Problem

[SRJesse]

I posted this in the technical form but I have a feeling not many people look at anything there! Here is my problem, or it may not be a problem at all.

Just bought an 89 240sx with only 95,000miles on it. There is something wrong with the transmission.

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. In fact, it never shifts never! ROFL Which kiinda makes me think its some kind of drag racing transmission. It works on one gear and is perfectly adjusted where the rpms should be. Torque is always there, no downshift when floored, not a up shift on the start. (REALLY REALLY STRANGE) Please let me know if you have any idea what could be wrong with it or if its possible its a different transmission like I said.

Thanks guys