Hi everyone this is my first time using a form. I have owned 3 Volvo cars over my life, a 240, 740 and now a 850. The 850 I just picked up and it has 160,000 km or 100,000 miles. Today when I turned the car on everything was fine, but when I put it into reverse the car started idling erratically. As soon as i put the car back into drive it stopped and the idling smoothed out. Any thoughts on what this might have been.

 

Welcome The first thing I would do is clean the throttle body and Idle motor.

I moved this to the 850 section.