I own a Caterham Seven Roadsport 1600 (Sigma engine) 125, registered 2014, mileage about 16,000. The car is not modified except for a exhaust bypass pipe in lieu of the catalyst (Caterham supplied part). The car has run very well for the last 5 years, except recently when I returned from a 800 mile round trip to South Wales, where the car experiences hesitation on starting from rest. This happens after a few minutes from ignition on and the engine warming up. With the car at a standstill, engine on idle, when I accelerate away, the cars splutters and hesitates/kangaroos, and then cuts-out to idle. This also happens when I'm in second gear accelerating. I have to gently control the clutch and accelerator to keep the vehicle moving, and reduce the hesitation. I have connected a MBE USB-CAN interface to the vehicle, and I notice 2 items; a) There is a 'Unknown Fault' in the ECU status box. b) The throttle site 1 voltage fluctuates between 0.0 to 0.4 V on idle of 920-950 rpm. (I see some people state the TPS voltage should be 1.05v, how correct this is I don't know) c) On reving the engine, the throttle voltage rises smoothly. Would you have any thoughts of where I should check, ie Throttle Position Sensor, EGR valve, ignition coil pack, Lambda sensor etc, and is there any known issue(s) associated with the above symptoms. Many Thanks Neil Claydon