I bought a 92 Range Rover which had just had its transmission replaced with a rebuilt one. From 3rd to 4th (or is it 2nd to 3rd), it really jerks. It works OK, and I have no other complaints, but it would be nice to stop it doing this.
Actually, from your description, it DOES NOT work ok!
Your rebuilt transmission comes with a warranty, but it may be a short one. Go back right away, and politely demand that the problem be fixed.
Otherwise, all repairs will be on your dime, and that could get very pricey. Do you really want to pay for another rebuilt transmission on this 17 year old vehicle?