Just a thought Paul, can you do a compression check? Sounds like low compression on one cylinder causing misfire at low revs. (possible piston rings blowing oil into breather system to cause high revs when changing gear?)
Re: Renault Master-erratic performance, missing at idle.
I thought it might be a hydraulic lifter issue and I have "Forte'd" it but without improvement.
Obviously, a proper compression test would represent a major amount of work (Glow plugs/Injectors)
But it would be interesting to listen to it cranking.
(At the risk of asking an embarasingly dumb question, what is the best way of preventing the engine from starting so I can hear it or use the Pico cranking tool)
Re: Renault Master-erratic performance, missing at idle.