ive got a 3.3 revo. when the car isnt running the servo's seem to respond to the controller perfectly, but while the engine is running both servo's seem to get the gitters. The throttle is worse than the steering but both are screwy. Is there a good way to figure out what the problem could be or has anyone ever had this problem before?
Try new batteries or fully charged ones. Then look to see if there is any kinks in any wires and if any of the copper wiring is exposed at all. Just search through a few of the threads here in the radio section and you will see others have the issue and how it was resolved.