On the plus side - Have just got had 2 lovely weeks in Cornwall

On the negative - While we were down there the van has gradually gone from starting 1st time no probs to needing the cold start fully out to start. I also get the occasional cloud of smoke when it kicks in. Once it warms up its fine (though it doesnt seem as 'sweet' as it used to be) I recently changed the oil/filter (gsf's finest).
I also think thats its using a bit of oil and it has started to judder in 1st and reverse - I have a hunch the two are related (maybe oil leaking onto plates) - any thoughts??. I have looked on previous posts and engine mountings have come up as a possible cause - how do you check if there worn

If it is contaminated plates can anybody give me an idea of a price to get it sorted - I realise the whole engine has to come out so am guessing its not cheap.
Many thanks
Ben
its a JX by the way.