Hello, I've recently bought a '54' plate C8 2.0 Diesel - I too have the same problem, the car seems to 'misfire', causing a loss of power, frustration to the driver (me!) but will then disappear for a few days only to re-appear for no reason. I bought it from a dealer who has offered 6mths national warranty, I guess I should take it to a Citroen dealer? Any advice..........