I have A170CDI year 2000. In damp/wet conditions car seems to missfire and jumps like a kangaroo, in dry conditions perfectly fine. Has anyone came across this before and if so any suggestions. Thanks.
Maybe you're getting water spalshing up onto your coil pack unit. With your bonnet open, looking downwards, behind the radiator, there should be a plastic cover with some cabling loom to your right(left of car) This black cover, if you have it, covers the ignition coil pack. If it's missing, the protection is gone.