Jerking when coasting in gear at low rpm

[assembled]

Hi, my 1.8TD with bosch pump starts to jerk at 1200 rpm and down when going downhill in gear. I have not driven this car for some years and perhaps forgot that it is supposed to be like that? My pump is rebuilt with mix and match of parts, timing can be off, idle is close to 1000 rpm. Otherwise runs OK, maybe a bit underpowered. Car sat for 8 years or so unused.

[Jaba]

It might be water in the tank as this will flow forwards while going downhill.

[assembled]

I think it was mostly because my accelerator leber was too far. I have unwinded the accelerator rest back until it stopped lowering idle rpm and then adjustwd idle with the hot idle screw. It is still not ideal, but so much better that I think this was the issue.

[Jaba]

Glad you found something.