Engine surges slightly with AC on, in drive, with foot on the break, so it happens at stoplights. I can make it stop by giving it a little throttle while keeping my foot on the brake and getting the RPM's up to about 950. It does not do it all the time. I told Range Rover and they replace the AC compressor. It still does it, just enough to be annoying. Has anyone else noticed this? Is it normal?