My grandfather drives a 2001 VW passat with a 4 cylander turbo and an automatic and he has started to have problems.

When he turns it on and goes from park to drive, the car basically revs itself a little and the car jerks up and down. The same thing happens when going from park to reverse and drive to reverse and vice versa. My grandfather took it to the shop and had two parts replaced (I don't know what they were, just that they are supposed to be replaced together for an issue like this) and the problem persists.

Anyone know what this is? Thanks in advance.

it sound like something to do with the idle air control.......... The computer is sensing the change in gears but it is not adjusting correctly and thus creating the surge/jerk when put into gear.........

Check for any engine codes and it may be somthing as simple as an idle air control valve............