Hi i know this is not a mercedes but it is a ssangyong musso and i know it should not be here but this a total plea desparation, the ssangyong musso has the om662 2.9 5 cylinder diesel non-turbo with manual gearbox built under licsence of the mercedes engine, i have looked on the internet with no luck to the problem. What happens is that when i accelerate or put my foot on the gas in 2nd or 3rd or 4th gear, the car gets all jerky like an elastic band and it happens about 1,300rpm to about 2,200 rpm then dispappears and then is smooth, it does not happen in first gear or when iam crusing in 5th gear, the engine starts instantly when hot or cold and idles smoothly, all filters have been changed 2 months ago,there is no air in the system or blockages, there is a throttle damper on the side of injection pump,cant see it being that as my other musso drives perfect without the damper, the pump was changed as the old pump was doing the same thing and i assumed it was worn, its so embarresing in traffic, make me look like a learner driver, any idea anyone