Hi Rob B,
Kieth at Brands Hatch is very Knowledgeable about the T16 Rover Engine, unfortunately so am I, it is by sorting issues with my engine to get it running sweet that I have come across all manner of issues.
Other TM folk have suggested possible causes and effects.
You need to investigate the patient then when you see what the problem is deploy the fix, there are a few quirks such as low battery voltage effects the MEMS unit and as John says the Vacuum pipe connected to the mems can become blocked with oil crud or break off, however I have disconnected my vacuum hose to the mems unit and the engine runs without misfire
I use a ODB reader and software to help with diagnosis and also have fine tuned my engine.
The software / odb gives readings of all sensors and the Lamda reading
Software and reader is on this link
http://memsdiag.blogspot.com/2015/01/memsdiag-what-is-memsdiag-memsdiag-is.html
