Disco 2 Guy in Brighton who is an expert on Discoverys

Hi all - I used to have the name of a chap in Brighton (I think) who was an expert on Discoverys - I need a head changed and few other jobs done. What I have is 2000 Series 2 - which I have had from new - its got about 150k miles on the clock and is beginning to throw vapour from the exhaust and also, slow to start in the morning. I poured a bottle of miracle cure in recently and it seems to have sorted the problem - however, I am sure that the fix is temporary.

Any suggestions appreciated.

Michael Mee