2000 Vauxhall Zafira loosing power

Hi i posted at start of wwek about ny zafira loosing power so i checked forumes and says egr so ive cleaned egr and still noluck then some one told me change fuel filter so did still the same car has no power when iget it upto 60 skight black smoke every so often car sometimes hasitates while moving has any one got any other clues what it could be i cleaned egr valve its the one with only a breather pipe attatched to it 2 bolts to get it off the block the egr valve fits onto will i need to also remove that block to cleanall the built up carbon inside looks black inside would it make a diffrence any ideas let me know thanks also the long bit on egr valve when you press in and you feel air feels a bit stiff should it be easy to push in ir is that way its ment to be thanks