The main reason for this "jumpiness" is that under, say, quarter throttle now, you're letting as much air as three quarter throttle with the stock TB. So before the new throttle body you had to mash the pedal to get the car going, and now you only have to press a little. Just wait till you get used to it, then drive someone else's car who doesn't have one. You'll probably miss it a lot, I know I do...
Nick