I stripped down the top end to replace the VP Gasket. so while I was there I changed the plugs and leads, when I put it back together it was running rough on idle, we checked the leads and there is no spark on any of the leads on the drivers side coil, took it apart again replaced the coils only to be left with the same problem...2003 Land rover disco

 

And you have both coil packs plugged in, each one has an independent connector from the ECM. If they are both plugged in, I'd check for power at the terminal ends of the harness connection. Might want to check fuses in the engine bay compartment fuse box (by coolant reservoir) and see if you find any blown fuses. Not sure if there are any, don't have a wiring diagram on hand,but worth checking.


Brian.