Why my VW touareg 2006 TDI jadder during stay?

I bought a VW Touareg End of August and car started to jadder 2 weeks ago. The car has 3 months warranty. I called the service where I suppose to take during warranty and I had to leave the car for a week and they said they had to change the gascate and it will be ok. They changed that which I had to pay becasue they mentioned this part is not under warranty, once I came out of the carage it started to jadder again since I was late I could not be able to go back there . So when ever I stoppped behind the red light it start to jadder randomly in different way then by pushing the accelerator it goes away but once I remove my leg it does start again. What do you thing the problem is and what option do I have? Thank you for your advice in advance