1997 (mk3) AstraVan Diesel 1.7TDi
Thanks to all those that helped with my recent clonking noise and shut-off 
solenoid problems.  Took the van for MoT today and it passed with flying 
colours.  Only problem now is a very annoying shaking on the overrun at 
about 1300 rpm.

It starts first time (apart from a slight hunting after been sat for several 
hours) and drives well but when I coast down a road with my foot completely 
off the throttle pedal, as soon as the revs drop to 1300rpm the engine will 
shudder quite badly.  I can best describe it like when someone selects the 
wrong gear (too high) and starts kangerooing down the road.  Now the funny 
thing is it seems to only do it at that particular RPM range. Once it drops 
lower than 1300 rpm the shuddering stops or if I use the throttle to 
increase speed it also stops.  It makes no difference if I'm coasting along 
in 2nd, 3rd, 4th or 5th gear, just as soon as it hits 1300 rpm on the 
overrun it bucks & shakes similar to someone blipping the throttle very very 
fast.  Any ideas welcome.

"Redwood"  wrote in message 
news:6g3ljuFe6hg3U1@mid.individual.net...
> 1997 (mk3) AstraVan Diesel 1.7TDi
> Thanks to all those that helped with my recent clonking noise and shut-off 
> solenoid problems.  Took the van for MoT today and it passed with flying 
> colours.  Only problem now is a very annoying shaking on the overrun at 
> about 1300 rpm.
>
> It starts first time (apart from a slight hunting after been sat for 
> several hours) and drives well but when I coast down a road with my foot 
> completely off the throttle pedal, as soon as the revs drop to 1300rpm the 
> engine will shudder quite badly.  I can best describe it like when someone 
> selects the wrong gear (too high) and starts kangerooing down the road. 
> Now the funny thing is it seems to only do it at that particular RPM 
> range. Once it drops lower than 1300 rpm the shuddering stops or if I use 
> the throttle to increase speed it also stops.  It makes no difference if 
> I'm coasting along in 2nd, 3rd, 4th or 5th gear, just as soon as it hits 
> 1300 rpm on the overrun it bucks & shakes similar to someone blipping the 
> throttle very very fast.  Any ideas welcome.

Could be engine mounts, injectors, injection pump, play in 
driveshafts/gearboxes, or a mix of those aswell as numerous other things.

Personally, I'd advise you just avoid cruising at 1300rpm.
If it gets worse, then look into it further.