flat spots/hesitation when engine high revs

I have a 99 passat 1.8T.
it drives superbly when cruising but when you put your foot down and give it some welly on occassions it will hesitate slightly in the higher rev range as if its losing power or the fuel is not getting through.

I have read wrong oil
blocked injectors
lose turbo pipes

any ideas

Possible turbo problem?

Possibly a bad maf sensor.

ALso check for vacuum hose leaks in the intake manifold area.