Suzuki Vitara Cuts Off While Driving On The Road ? Why do you think it is?

Hello friends, I have a problem, we could not solve it, masters, my vehicle is suzuki vitara 1.6..1.6 valve question, there is no problem while driving on asphalt, but when going to the stabilized road, the electricity cuts off, spark plug, spark plug cables, distributor cap, spark plugs all have been changed, but my question still continues, I would appreciate if you could help, thank you