this might help??
00518 P0121 Throttle Position Sensor - Signal Out of Range (G69) Also check for loose ECM
power relay.
and this
Starting in 1996 on OBD-II vehicles, Volkswagen began using an electric throttle control module to control the throttle plate. This throttle control module contains an electric motor that actually moves the throttle plate and two potentiometers that monitor throttle plate position and requested throttle position.
The throttle controller is synchronized to the powertrain control module (PCM) electronically. This matching process allows the PCM to memorize the closed throttle, wide-open throttle and pre-start throttle positions.
If power is lost to the PCM or throttle controller for any reason (disconnecting the battery is the most common reason), the synchronization between the PCM and throttle controller is erased!
This synchronization is known as the "Basic Setting." As hard as it may be to believe, basic settings are stored in volatile memory and are erased whenever power is lost from the PCM or throttle controller.try the disconnect battery for 5 minutes thing first and see if it comes back..
