Volkswagen Vento

To all sifu......

Need help here. Currently having problem with my throttle body for 4G13 engine (Proton Wira fuel injection).
REV up & down non stop (air-cond off).
REV normal when air-cond on but will be REV up & down once air-cond temp automatically cut off.
Workshop checked with the reading system said that there is 0 step. Must change new throttle body. Inside gears already replaced last year.
If, look for new throttle body. Can I use 1600cc or 1800cc throttle body from proton as...