intermittent clutch judder with new clutch & flywheel

hi all

i have intermittent clutch judder at low revs on my 1.9 tdi 105ps 6 speed
ive had the clutch and flywheel done with genuine parts approx 900 miles ago
if i apply more throttle the juddering is not as bad
just wondering if it could be an engine mount on it way out because sometimes the car shakes very slightly at traffic lights with the clutch in or out

50% of the time it doesn't judder at all and pulls off normally, im not sure whether its heat related or not but it never seems to do it when cold

any advice will be most appreciated as always

any ideas

last bump before i give up on any replies??