Loss Of Power Above 45mph

[DIY]

Hi - I have 01 plate galaxy 1.9 TDI (115bhp) - It drives fine up to 45ish mph and then foot to the ground, it struggles to get above 70mph. I was adivce to replace the maf sensor - this has been replaced but same problem. I have tried disconnecting the maf sensor and notice a differance in performace and mpg was lot worst - i assume this proves the maf sensor is working. any ideas what i shoud try next?

 

Thanks in advance

[zorgman]

what happens if you turn ign off n on does it fix it if so turbo, i would still go for turbo tho check all pipes inc vac pipes