hi guys, as the creator of this thread its good to see so many people trying to help, and also to know that other people are having the same problem tracing the problem.

anyway heres an update

i have been driving my car around for a while now with the speedo unplugged to stop it juddering and as mentioned before this seems to make it driveable, although sometimes (it may be in my imagination) i think i car feel the car juddering very very slightly. however if i plug the vss back in, the problem is exaggerated tenfold.

the vss signal is used for an engine management subfunction known as active cirge damping. this function uses several other sensors and is designed to smooth driver input and reduce sudden jolts of torque in the drivetrain.

now i have been giving this some thought, and i have decided that the rough idling is indeed related to the juddering problem. The engine management system uses the crank sensor to maintain idle between set parameters......the link here is that this same sensor is also factored into active surge damping.

My thoughts now, and my plan of action is to try unplugging the crank sensor as this engine management system does not actually need it to run. I know it will go into a mild stage of limp home mode as it will use the needle lift sensor as a substitute signal for engine rpm.

ill let you all know how i get on .
also i may try scoping various signals at the ecu to check them for noise.