Polo 6N2 1.0 Ramdom Multiple Misfire

[½cwt]

Got a 1.0 Polo with 'random multiple' mis-fire according to VAG-COM lite. Have changed plugs which cleared it first for about a week. It has now returned and I've fitted replacement leads and ignition pack from a known good runner but still have same mis-fire and error code which returns after clearing. It also intermittently reports an EGR fault.

Any ideas please?