I was having that problem. 6months ago i would be driving and the rpms would jump all over and car would stall. i thought it was the rpm sensor. But it wasn't. it turn out to be the conection right next to the battery on the body of the car. Where i live it rains alot and the conection was coroded. One way to test this is to grab the cable and wiggle it. if car dies you know. So i cleaned sand paper so contacts were shiny. then i put some electrical grease on the contacts to prevent problems in the future. No problems sense.