running/ boost issues

Hi people iv just got a vrs and having a few issues with it. it had been re mapped so i put the scanner on and it come up with a few codes but only ones that come back on it the intake motor flap that has been removed and glow plugs. it starts first thing in a morning no probs.

anyway iv had it re mapped again and it was still the same

i then disconnected the maf sensor and it ran much better, i looked the part number up on google and it came back as a 1.4 polo maf so i put a golf pd 130 on and seems to have made it much better but now and then it will not boost but when it does it seems to pull strong. i have cleaned the turbo out ect and works ok. 

tried another map sensor on and its still the same. 

it also black smokes when its wont boost and has a diesel knock in 1st and 2nd sometimes.

im now at the stage where im not sure what to try now so could do with a diagram to check the vac pipes from the n75 the egr has been removed but do both the pipes need to be blanked off ?

http://s199.photobucket.com/user/simi240/media/10407676_10203731488660927_1171295185769563403_n.jpg.html