2.0 hdi 406 w reg jumping when driveing

[johnnytab]

hi i have a problem with my 406 when im driving around 20 25 mph between 2000 3000 rpm it feels like it is surgeing/jumping when this happens it makes a crunching noise sounds like its coming from the drivers side maybe the drive shaft also sometimes engine management light comes on and the car wont go past 3000 rpm in any gear could these problems be linked any help would be great thanks