The gearbox fluid flush will not work, even if you have changed your oil the second time.

The reason between CVTF and ATF is the viscosity of the oil due to the temperature change. There are things like traction and friction difference in those oil.

I wouldn't say if you found the jerkiness one day, your CVT has gone busted.
It is not like it developed sludge overnight.

Some culprit reasons can be, your foreman loaded more oil than it is required. Although the Jazz takes in 4L, it basically just needs to be around 3.6-3.8L. You don't need to fill it to the brim.
I had this slight jerk last time, and told them to take some out.
Too little could also send similar symptoms...

Have you change your battery lately?..
Have you checked your spark plugs?.
Have you moved/clean your Throttle body lately?...MAF sensor could be dirty...

All the above can send similar "jerk".

If you are having issues of the jerk around 15-25km/h slow driving paces...or heavy traffic driving...that could most probably be the gearbox .

Hope this helps.
I own a first gen Jazz (GD3), and driven it for 6 years on top of the existing 3 years.
No issues. I religiously service my oil, every 4-5 months, regardless mileage.
It is sold.

This post has been edited by Heroicage: Sep 17 2014, 04:06 PM