I just got a used '03 XC70 about a week and a half and about 8 days ago the thing has been acting really weird.

The check engine light is on. About 20% of the time the engine won't fire (turns over fine) and when it does start the RPMs go crazy and the car tries to lurch forward. Like the RPMs will sit at 1 and jump up to 2 and a half, fall down to one, jump up again and again and it even does that in park. If I'm in drive without depressing the brake pedal it literally jumps forward.

What is wrong with this car? How do I get this fixed? Will any mechanic do, or do I need to take it to a Volvo dealership? Any advice is appreciated.

 

Did you ever get this fixed? What was the issue? My 2001 S40 is doing the exact same thing. Except it died in an intersection. I just had it towed. Kind of interesting that it happened a year to the day after your post.

 

Your 03 sounds like a throttle body issue. First thing that I would do is pull it and clean both sides. Then, reinstall and see if things improve.