When I am stopped at light, my car seems to lunge forward and idle real rough. on 2004 Kia Amanti

Just had it serviced at Kia dealer and timing belt changed. They have tried fixing it but could not. any ideas?

Asked by for the 2004 Kia Amanti
I would take it back to the dealer and tell them to fix it you could have a timing problem which could be due to timing belt change
they had it for 6 weeks trying to figure it out. Checked timing belt twice and did a valve job. Don't really think they know what they are doing.