avengerpenguin,
TBH we are all speculating on what may be wrong.
I'ts worth getting your car to someone that knows Cossies well, to give it a check over. I would reccomennd a leak down and a compesssion test as a first course of action. It may be that there is not a lot wrong after all..then again.
I see that you are in Bristol, I am sure that there are one or two peeps from Bristol RSOC that could check your car over, or at least reccomend somewwere local to you that knows what they are doing, and wont try to rip you off
Maybe change the title of this thread (EDIT) to "Bristol/Glos peeps Cosi help needed please"
=================================================