OK, I got a new one on my Discovery. When I step on the gas while the car is in reverse, the engine revs up even when you take your foot of the accelerator pedal. The first time it happened I was climbing up some stairs at Little Moab. It was a little un-nerving being pushed backwards down some rock stairs with a drop off on one side but back to the story. Now, ever since then any time you accelerate in reverse the engine want to keep revving. Once you stop and place the car in neutral, it revs to about 2000-2200 rpm and won't go down until you give the pedal a good stomp, then it will return to normal. When you back up without pushing the pedal it stays in idle. In drive the car acts normal with the exception of on cold starts the idle would sometime "pulsate". I have changed the IACV valve and cleaned the airflow sensor and the cold idle problem seems to have gone away. But the reverse problem is still there. Any Ideas?? The Disco is an 03.