My Focus estate 1.8 TDCI 02 72,000miles as developed a missfire at very light throtle load only at 1900 revs though, if i accelerate hard in 2nd gear the missfire will go for a while, but on acceleration there is loads of black smoke..oblem could Could anybody give me any possible clues to what the problem could be ...any advice greatfuly accepted..

these are the classic symptoms of a split intercooler pipe which is the large pipe on the bottom of the egr valve.