my 2l petrol vibrated VERY badly on acceleration. turned out to be the inner tripod joints on the drive shafts had leaked grease and worn out. so worth a check.

also, as said, worth checking the torque mount (i've replaced mine for poly but it does make the car vibrate more on idle) and also worth checking the other bushes and shocksover too especially if its done over 100k as they'll be getting on a bit.