Ok, not sure where you got those fault definitions but they are incorrect for your specific vehicle.
1999 Saab 9-5 Wagon (9600) V6-3.0L Turbo (B308)
P1260 Throttle Return Spring. Too Low Force
P1251 Throttle Motor. Full PWM in Closing Direction.
You will need to replace the throttle body assembly in order to repair and get rid of these 2 codes.
Being an 18yr old vehicle, this failure is not unusual or sign that the vehicle is junk.
If for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT/3 STARS OR HIGHER today. Please reply and let me know why, so I can help more/better. All follow up responses are FREE, after completing the required rating
Please remember to rate service using the separate rating page. Thank you
Please note that if you have a subscription service, you still are required to rate service, however you are not charged again. This is just so that your expert is credited for their time and services. Thank you.