[Arosa] Prbleme after Werstatt stay with the idle

Dear community, today it’s not a problem with our Meriva but with our little Arosa. I had my Arosa dragged into the workshop on Monday because the coolant pump broke. They then renewed the pump and changed the timing belt. During the test drive they found out that the engine was running restlessly, and then looked there. In the ignition distributor what was broken, and then it was also changed, including spark plugs. Nu n I picked up the car yesterday from the workshop, drove about 2-3 km and then had to stop at a traffic light. The speed varies very strongly down until the engine went out. I started this again because I thought I made a mistake and at the next traffic light the same problem. Then I turned back to the workshop, drove into the hall, they then read out the error memory, and found nothing, the working mechanic then has a test drive made and could not notice anything. I am then again going, after a short time again the same problem I went again, he looked everything again if he had built something wrong together was not like that. He meant now I should drive around so for a few days, it would probably exist if not I should come over again. Did any of you have a similar problem? The following “repairs” were carried out: timing belts and water pump ripper belts Ignition vertebra Eileer spark plugs. Thanks for your help! Dear greeting Timo aka Linux