help! juddering on overrun

[binman jim]

ive got a ford puma 1.7. but a the moment at 1700rpm, only on the overrun she judders(kangaroos)quite violently. there's no misfire's and its pulling fine. ive had a ford technician have a look at it and he says there's no visible problems so i will have to get it hooked up to diagnostics.
i was just wondereing if someone's had this problem before and could tell me what the problem is.
p.s, when moving and in neutral it stays at 1300rpm and doesnt drop back down to normal idle.

[Zad]

I think I remember reading that they are intended to maintain engine revs whilst in motion but the clutch is depressed, in order to give smoother gear changes. Not sure about the popping on overrun. Perhaps check all the vacuum pipes to the MAP sensor etc are clear and not leaking. Check the condition of the plugs and HT leads, and the connections to the coil pack.