Was your problem sorted out , as I have same symptoms with my Disco 1 1999 model and all started with a faulty Distributor , that I had changed with a used one , put on new Lucas Cap and New set of Original Cables . Changed the Spark Plugs, changed the MAF and the IAC Sensor, cleaned the throttle body, changed the fuel filter and the shrugging, spluttering, not running smoothly is there and some times it does accelerate and sometimes it doesn't cope !!! On neutral you can still hear the exhaust noise note very stable as it goes bhbhbbhbhbbbbbhbhbhbhbbbb like cough !!!