The gas station annoyance is due to the charcoal canister not being able to vent the air inside the tank as it fills up. The clicky sound you hear from the engine is the vacuum unit for the evap system (its marked MOT) - remove the hoses and clean it with some WD40 or carby cleaner.

When I had these misfire issues the problem was bad spark plugs - I changed all 12 of them.

Most people have also reported that the cats had broken up and plugged the exhaust which caused the misfire.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)