I just changed the throttle body on my 98 jetta 2.0 engine.The idle is now stable but when I get up to at certain RPM, it really drops off. It almost stalls and then picks up again over and over. Does the new TB need to be programmed? Is there a wat to 'reset' it? thanks! jp

unplug the battery for 15 minutes, leave the car in the on position but do not start it for 5 minutes. Then start the car.
If you have an automatic transmission then you may be out of luck, probably end up taking it to the dealer.