E30 M10 engine running problems

[Kevsparky]

My e30 318i M10. Starts and runs perfect, however, as soon as its driven, it seems to lose a cylinder. Have changed plugs, leads, and fuel and water pump. Car has only done 78k miles.The car has stood outside for 8yrs so just about to embark on restoring it. Any ideas what the fault could be?

[sadham]

My m10 seemed to misfire at one point. Garage fixed it for free something about water in distributor cap iirc. Maybe worth a check see how healthy the cap looks inside.