Hello Don, I followed your instructions and it would seem that up to now the engine is running as it should again with no missfire or intermittent loss of power.
To get better access to the
valve I also removed the air regulator mounted above it which I am pleased I did. This allowed me to see the 2 interconnecting ports which the
valve controls the flow of gases passing through.
One port was clogged up by as much as 50% of caked
and carbon deposits and the other 15%. I used an end of a jubilee clip to scoop and scrape out all the muck. I was truly amazed that the engine would actually start never mind run found in this state.
I bought myself a manual on the engine and I was surprised that it does not suggest periodically cleaning the valve (only how to fit a new one) so every 9000 mile from now on it will get a clean out.
It goes without saying I am grateful for your time and help as it has probably saved me a small fortune. I went to my local Ren agent about the problem and they were suggesting I fit a new turbocharger regulating solenoid at a cost of £40.00. So there you are, it is good to talk to someone who knows what they are talking about.