Car starts only with gas and jerks in idle

Hello dear community, I have again a problem with my Twingo (Bj 2014, almost 35000 km) Since the weekend it only starts when I give gas. During the ride there are no abnormalities. Only if I stand at the traffic light I have to give constantly light, because he otherwise like a tractor is jerking and threatens to go out. Was with the symptoms already in the workshop where they changed the battery. At first with success. Only now it is just worse. Was today again in the workshop and got only on 6.03. a date ???? He meant it might be on the steering chain but I think that is improbable, or? Maybe spark plugs or something? I have no idea and fear to be pulled over the table. Maybe you have an idea. Thank you already LG Anni