[Azimov]

Seems to me there are only two possibilities. Interference, or a loss of signal due to connections. Try it in a different room and see if the problem still exists. If not, it's your electronics in the house. If it still stutters, you've got a bad solder join somewhere. Either the car or controller antenna connections most likely. There is a remote chance that your cars antenna coil needs tweeking, but I doubt that.