as an aside, my car was identified as having new injectors fitted under recall, by previous owners. except they were not coded to the car. I had a stench of fuel every now and again, these have now been re-fitted and re-coded the smell has disappeared, blue smoke on crank/fire remains.
H, did you have your head stripped and cleaned (valve seats also) to remove carbon build up?
My thinking is for a puff on cold start, it has to come from the combustion chamber as everything else is too cold to burn oil.