hesitating under boost
 

Hi all,new to Scooby net!
Bought a MY99 uk turbo last week car has been great up to now, but noticed Serious hesitation under full throttle a few days ago, changed fuel to optimax but still having the same problems.
I have read quite a bit about this possibly being down to a faulty MAF sensor but thought first id seek some guidance before running off and blowing my money, any idea's or suggestions are greatly appreciated,
cheers

maf, coil pack, plugs, plug leads ...