occasional juddering

[john]

mk1 berlingo 1.4 petrol, the juddering comes and goes, it could be at as low as 35mph or 50-60 or anything in between, if i put my hand on the gearstick you can feel it through that as well as through the steering wheel, if feels more violent through the stick, i dont just mean a bit of vibration i mean proper shaking, if i dip the clutch it gets better (or it may just be my imagination), im going to check mounts, suspension parts etc today (passed its mot 2-3 weeks ago so dont expect to find anything), any ideas as to what it is and why it comes and goes?