car won't idle down
 

I worked on my daughters 1987 Volvo 240 with the 4 cylinder engine. The car ran fine before I jacked it up and worked on the exhaust and after setting the car back down the car won't idle down. It wants to race, the idle is so fast that if you have the car in drive it will go about 30 mph. I didn't do anything under the hood at all. Does anyone have any clue's on where to start troubleshooting this. Thanks

Happened to my volvo too. I had to reset the throttle position sensor, and did an intake cleaning.