slips b4 shifting into 3rd?

i have a 99 saturn sl2 just bought it from a friend of mine he said its always done it since hes had it and the trans was rebuilt before he bought it 50thousand miles ago does it just shift bad or wat ive never been in a saturn that didnt have a lazy tranny it also has an engine light so im wondering if it has to do with transmission codes and it does the same thing if u manually shift it threw the gears it seems like it slips when the rpms get abought 4grand to about 5grand then it shifts and is fine the trans fluid is still red and doesnt smell burnt any ideas anybody?

i have a 99 saturn sl2 just bought it from a friend of mine he said its always done it since hes had it and the trans was rebuilt before he bought it 50thousand miles ago does it just shift bad or wat ive never been in a saturn that didnt have a lazy tranny it also has an engine light so im wondering if it has to do with transmission codes and it does the same thing if u manually shift it threw the gears it seems like it slips when the rpms get abought 4grand to about 5grand then it shifts and is fine the trans fluid is still red and doesnt smell burnt any ideas anybody?
does anybody think the impute shaft nut is loose would that make it have problems with the trans? cuz it does have a slight lag in reverse it doesnt slam or anything is that nut difficult to replace do i need to pull the trans?

Im not a stikler for grammer by any means, but PLEASE use a period. I read at least 25-30 posts a day on 3 different forums and it hurts the eyes when you dont break up your post. other wise I will pass over yours and not answer it.

Replace the ECTS. Make sure the connecter is clean and corrosion free. While your out get the codes scanned. The tranny fluid and filter should be changed every 15K at least.

A loose input shaft nut results in a loss of a particular gear and MAJOR reverse slam.

NOTE: The torque converter locks and unlucks in 2, 3, and 4th gears unlike other trannies.

alrite i will try to break up my text srry about that. and i will also try that sensor and a trannie fluid and filter thanx alot fot the quick reply