I am having the same problem with the AC on, I took my car in last week they said it was normal for the RPM to fluctate but my car almost dies then jumps with my foot on the brake. They also said it was low on freeon they filled it up and claimed the fluctuation was not as extreme, It's the same!!!!
I am going back to a different dealer tomorrow morning. I have had my car for a year this problem just started I use the air all the time. Another problem I had was while braking there was a loud grinding type noise they looked at the brakes and they said there was no problem but it stopped. My friend has the same car shes having the brake problem now.
