I've kinda got the same problem but mine doesnt fly drove fine on my way out and was ok most of the way back from a 60 mile trip, about 5 miles from home it lost power, would still go but feels like she's running on 3 instead of 6 Cyclinders? had a quick look under the bonnet but was too busy to have a proper play, started her again but still the same. I've got 4 days off starting tomorrow so i'm hoping to get to the bottom of it. Plugs, Leads then....?