Had a problem for a while with my 99 turbo 2000... if I am holding a steady speed, for example 30mph in 3rd I notice the car seems a little juddery - nothing massively noticeable but it is definitely there constantly.
Does not seem to be happening under acceleration or boost but it makes driving around town irritating.
Any ideas of probable causes?

 

could be the MAF sensor -- they were noted to be 'fragile' on this model...

 

Mine was exactly the same for months, found a split in the pipe from airbox to turbo and mass air flow not reading right, stuck new pipe on it and a afm and it was sorted.