Forgot to add, there is an ignition amplifier, screwed onto the bracket that holds the ignition coil, they do get warm, the amplifier uses the bracket as a heat sink, haven't had one fail, but have heard of failures. If fitting a new one there should be some heat conductive grease supplied.
I have had an ignition module fail, BUT when it did the engine would not fire at all , so I don't think it fits these symptoms.
I suspect a poor wiring connection somewhere in the loom, but finding it can be very tricky and time consuming.
I don't think that generic code readers work with the Rover V8 engine (until the introduction of the GEMS system?) as it needed the Rovercom to interrogate the ecu, but my knowledge here is somewhat scant.
I have also had an air mass sensor (technically the air mass sensor measure the mass of air going through it , rather than the volume which is measured by an air flow sensor, but both fulfil the same role) fail, and it gave poor running conditions (so not the same symptoms again) , but would let the engine start. The only way I know to check this is to replace the unit with one that is known to be in good working order.
Good luck
