I have changed fuel pump in tank, fuel filter, leakoff pipes, re seated no6 injector, i have run it from the injection pump straight into a pot of deisel also run it with coolant temp sensor and air temp sensor disconnected and it still running lumpy on tickover a loss of power. It has been good as gold today but that evening it started playing up again. It sounds and fills like loads of air in the fuel but if the pump in the tank is pushing from the start of the system not like a lift pump half way through the system, where would the air get in. Please help