Also, bearing in mind she runs lovely when cold, is there anything else I should be checking?
Just to clarify symptoms:
Rough idle when warm (sometimes cuts out)
Bad mpg
When warm, revs seem to "hang on" a bit before dropping.
I'm no mechanic but I'm convinced it's running on choke (or equivalent) all the time.
How does the engine know when it's warmed up to adjust fuelling etc?
Thanks again