Overfuelling???

Hi all, my 1998 300tdi auto es, 130,000, egr and decat now done, and brand new filters fitted,intercooler cleaned and new pipes on way, top hose and elbow swell as revs increase so no delamination i think, however i have ordered a set of silicone just to be on the safe side, (thanks to you guys she feels complety different to when i had her now), when i pull away from standstill if i floor it i get a great plume of black smoke out the rear, if i apply fuel gradually no problem, same when i tow if i put my foot down without kick down blacksmoke if i apply fuel gradually no problem, and if i kick down when towing smoke dissapears completly any help!!