How much should it cost to change/repair timing and how long?Parts and labor?

What is your question?

The engine has 230k + miles on it and shows the timing (?) was worked on at 100k. The vehicle doesn't idle any more. It sounds like it is running between 30/40 mph and sometimes tries to jump when at a stop light or sign.

What makes this problem better or worse?

worse when engine is cold

How long has your 1999 Toyota Avalon had this problem?

about a month