Hi, I have a brand new Volvo s80 3.2 front wheel drive car. The first problem is the check engine light cam on at 800 miles, the rpms were jumping up and down when I was below 25 mph and the car would almost stall. Got it back they changed a cam sensor, now the rpms still jump up and down below 25 mph, they will jump from 1000 rpms to 2000, back to 1500. Everything is fine at higher speeds but this does not seem correct, can you please provide some feedback. Thanks.