Fluctuating idling speed for 1996 VW

a couple of things need to be checked first...the excessive idle variations can be caused by a lean condition....i've seen air leaks and contaminated mass airflow sensors cause these symptoms and idle speed fault codes...i would check this first....these electronic throttle bodies need to be reset and calibrated using a vag-com(volkswagen factory) diagnostic tool or an aftermarket scan tool that uses the vag-com software(snap-on scanner,launch x-431)....i would check for the lean condition and repair it if necessary and reset throttle body calibrations with the scan tool before condemning the throttle body...vw mass airflow sensors are susceptible to contamination and will cause these conditions....don't replace the throttle body until its been properly diagnosed and not just had the codes read....

thank you for the fast reply. But should I expect my mechanic to have such vag-com diagnostic tools...where would I get one?

usually only techs who do volume volkswagen work have them....a snap=on scanner with the european software or the launch x-431 cost over 2000.00...there is a company called Ross tech that sells the software and cables to turn a PC into a vag-com scan tool for about 600.00... www.ross-tech.com ....maybe your mechanic might want to invest in it if he is looking to handle more volkswagen work...there are so many tests that volkswagen has that are built into this software that its a must for accurate volkswagen repair....