Micra K10 Idling problems

My Mirca K10 (78,000 km) has idling problems that may be related to the electrics. If I turn on the passing light, the idling speed increases by 300 – 500 rpm. ASU is fresh. I found nothing. I turn the idling on the throttle stop on idling speed it runs, if I’m lucky, for a few days also o.k.. Suddenly it goes off at the traffic light again. Then I turn the throttle throttle lock Ag again up, he makes a good 1700 – 1900 rpm in idle mode (if the light is switched on). Idle mode is not in fact adjustable. Spark plugs new, air filter is also new, valves are set. With a sporty left-hand turn, I also run out. Bowden trains I checked, everything free, the same applies to cables, all correctly laid. Somehow, I don’t care about this phenomenon. I don’t have a bug anymore on the workshop. And if I have bad luck, I get a monster bill and have the same problem at the next traffic light. Who else can think of? Thanks !!! Oh yes: The phenomenon existed even before the ASU. I bought the car with 38,000 km. Lief super. At 50,000 km this car (ex-rentner motor vehicle) came the first time from B. to F. on the highway. Once in Frankfurt, it went out of my way for the first time. Since then I have to fight with the problem.